| Message ID | 20220421102041.17345-2-johan+linaro@kernel.org |
|---|---|
| State | RFC |
| Headers | show |
| Series | phy: qcom-qmp: add support for pipe clock muxing | expand |
On 21/04/2022 13:20, Johan Hovold wrote: > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > output generated by the PHY before powering on the PHY and restore the > default source during power down. > > Add support for an optional pipe clock mux which will be reparented to > the generated pipe clock before powering on the PHY and restored to the > default reference source on power off. > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > --- > drivers/phy/qualcomm/phy-qcom-qmp.c | 71 ++++++++++++++++++++++++++--- > 1 file changed, 65 insertions(+), 6 deletions(-) > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c > index 7d2d1ab061f7..bc6db9670291 100644 > --- a/drivers/phy/qualcomm/phy-qcom-qmp.c > +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c > @@ -3292,6 +3292,8 @@ struct qmp_phy_combo_cfg { > * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs) > * @pcs_misc: iomapped memory space for lane's pcs_misc > * @pipe_clk: pipe clock > + * @pipemux_clk: pipe clock source mux > + * @piperef_clk: pipe clock default reference source > * @index: lane index > * @qmp: QMP phy to which this lane belongs > * @lane_rst: lane's reset controller > @@ -3311,6 +3313,8 @@ struct qmp_phy { > void __iomem *rx2; > void __iomem *pcs_misc; > struct clk *pipe_clk; > + struct clk *pipemux_clk; > + struct clk *piperef_clk; > unsigned int index; > struct qcom_qmp *qmp; > struct reset_control *lane_rst; > @@ -3346,6 +3350,7 @@ struct qcom_qmp { > void __iomem *dp_com; > > struct clk_bulk_data *clks; > + struct clk *pipe_clksrc; Please move this to qmp_phy too. > struct reset_control **resets; > struct regulator_bulk_data *vregs; > > @@ -5355,6 +5360,42 @@ static int qcom_qmp_phy_init(struct phy *phy) > return 0; > } > > +static int qcom_qmp_phy_pipe_clk_enable(struct qmp_phy *qphy) > +{ > + struct qcom_qmp *qmp = qphy->qmp; > + int ret; > + > + ret = clk_set_parent(qphy->pipemux_clk, qmp->pipe_clksrc); > + if (ret) > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > + > + > + ret = clk_prepare_enable(qphy->pipe_clk); > + if (ret) { > + dev_err(qmp->dev, "failed to enable pipe clock: %d\n", ret); > + goto err_restore_parent; > + } > + > + return 0; > + > +err_restore_parent: > + clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > + > + return ret; > +} > + > +static void qcom_qmp_phy_pipe_clk_disable(struct qmp_phy *qphy) > +{ > + struct qcom_qmp *qmp = qphy->qmp; > + int ret; > + > + clk_disable_unprepare(qphy->pipe_clk); > + > + ret = clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > + if (ret) > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > +} > + > static int qcom_qmp_phy_power_on(struct phy *phy) > { > struct qmp_phy *qphy = phy_get_drvdata(phy); > @@ -5379,11 +5420,9 @@ static int qcom_qmp_phy_power_on(struct phy *phy) > } > } > > - ret = clk_prepare_enable(qphy->pipe_clk); > - if (ret) { > - dev_err(qmp->dev, "pipe_clk enable failed err=%d\n", ret); > + ret = qcom_qmp_phy_pipe_clk_enable(qphy); > + if (ret) > goto err_reset_lane; > - } > > /* Tx, Rx, and PCS configurations */ > qcom_qmp_phy_configure_lane(tx, cfg->regs, > @@ -5478,7 +5517,7 @@ static int qcom_qmp_phy_power_on(struct phy *phy) > return 0; > > err_disable_pipe_clk: > - clk_disable_unprepare(qphy->pipe_clk); > + qcom_qmp_phy_pipe_clk_disable(qphy); > err_reset_lane: > if (cfg->has_lane_rst) > reset_control_assert(qphy->lane_rst); > @@ -5491,7 +5530,7 @@ static int qcom_qmp_phy_power_off(struct phy *phy) > struct qmp_phy *qphy = phy_get_drvdata(phy); > const struct qmp_phy_cfg *cfg = qphy->cfg; > > - clk_disable_unprepare(qphy->pipe_clk); > + qcom_qmp_phy_pipe_clk_disable(qphy); > > if (cfg->type == PHY_TYPE_DP) { > /* Assert DP PHY power down */ > @@ -5777,6 +5816,8 @@ static int phy_pipe_clk_register(struct qcom_qmp *qmp, struct device_node *np) > if (ret) > return ret; > > + qmp->pipe_clksrc = fixed->hw.clk; > + > ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &fixed->hw); > if (ret) > return ret; > @@ -6091,6 +6132,24 @@ int qcom_qmp_phy_create(struct device *dev, struct device_node *np, int id, > qphy->pipe_clk = NULL; > } > > + /* Get optional pipe clock mux and default reference source clock. */ > + qphy->pipemux_clk = of_clk_get_by_name(np, "mux"); > + if (IS_ERR(qphy->pipemux_clk)) { > + ret = PTR_ERR(qphy->pipemux_clk); > + if (ret == -EPROBE_DEFER) > + return ret; > + > + qphy->pipemux_clk = NULL; This makes the driver ignore every possible erorr except -EPROBE_DEFER. However the driver should behave in quite the oppposite way. Please use devm_clk_get_optional() instead. It would do that in better way. Not to mention that this code leaks a refcount on the clock. > + } else { > + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); > + if (IS_ERR(qphy->piperef_clk)) { > + ret = PTR_ERR(qphy->piperef_clk); > + return dev_err_probe(dev, ret, > + "failed to get lane%d piperef_clk\n", > + id); > + } > + } > + As a second thought. This needs to be more explicit. If the chipset requires the pipe clock remuxing, we must fail if the clocks were not provided. So depending on the qmp instance/property the driver should either use devm_clk_get() (instead of _optional) or skip this block completely. But this will not work with earlier DTS files. > /* Get lane reset, if any */ > if (cfg->has_lane_rst) { > snprintf(prop_name, sizeof(prop_name), "lane%d", id);
On 21/04/2022 13:20, Johan Hovold wrote: > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > output generated by the PHY before powering on the PHY and restore the > default source during power down. > > Add support for an optional pipe clock mux which will be reparented to > the generated pipe clock before powering on the PHY and restored to the > default reference source on power off. > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > --- > drivers/phy/qualcomm/phy-qcom-qmp.c | 71 ++++++++++++++++++++++++++--- > 1 file changed, 65 insertions(+), 6 deletions(-) > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c > index 7d2d1ab061f7..bc6db9670291 100644 > --- a/drivers/phy/qualcomm/phy-qcom-qmp.c > +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c > @@ -3292,6 +3292,8 @@ struct qmp_phy_combo_cfg { > * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs) > * @pcs_misc: iomapped memory space for lane's pcs_misc > * @pipe_clk: pipe clock > + * @pipemux_clk: pipe clock source mux > + * @piperef_clk: pipe clock default reference source > * @index: lane index > * @qmp: QMP phy to which this lane belongs > * @lane_rst: lane's reset controller > @@ -3311,6 +3313,8 @@ struct qmp_phy { > void __iomem *rx2; > void __iomem *pcs_misc; > struct clk *pipe_clk; > + struct clk *pipemux_clk; > + struct clk *piperef_clk; > unsigned int index; > struct qcom_qmp *qmp; > struct reset_control *lane_rst; > @@ -3346,6 +3350,7 @@ struct qcom_qmp { > void __iomem *dp_com; > > struct clk_bulk_data *clks; > + struct clk *pipe_clksrc; > struct reset_control **resets; > struct regulator_bulk_data *vregs; > > @@ -5355,6 +5360,42 @@ static int qcom_qmp_phy_init(struct phy *phy) > return 0; > } > > +static int qcom_qmp_phy_pipe_clk_enable(struct qmp_phy *qphy) > +{ > + struct qcom_qmp *qmp = qphy->qmp; > + int ret; > + > + ret = clk_set_parent(qphy->pipemux_clk, qmp->pipe_clksrc); > + if (ret) > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > + > + > + ret = clk_prepare_enable(qphy->pipe_clk); > + if (ret) { > + dev_err(qmp->dev, "failed to enable pipe clock: %d\n", ret); > + goto err_restore_parent; > + } So, what you do here is you manually set the parent of GCC_PCIE_1_PIPE_CLK_SRC to PHY pipe clock right before enabling GCC_PCIE_1_PIPE_CLK and set it back to XO after disabling GCC_PCIE_1_PIPE_CLK. My proposal is doing exactly the same, but doing that automatically through the clock infrastructure. After removing pipe_clock handling from pcie driver itself, we can be sure that nobody is playing dirty tricks around the pipe_clock. > + > + return 0; > + > +err_restore_parent: > + clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > + > + return ret; > +} > + > +static void qcom_qmp_phy_pipe_clk_disable(struct qmp_phy *qphy) > +{ > + struct qcom_qmp *qmp = qphy->qmp; > + int ret; > + > + clk_disable_unprepare(qphy->pipe_clk); > + > + ret = clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > + if (ret) > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > +} > + > static int qcom_qmp_phy_power_on(struct phy *phy) > { > struct qmp_phy *qphy = phy_get_drvdata(phy); > @@ -5379,11 +5420,9 @@ static int qcom_qmp_phy_power_on(struct phy *phy) > } > } > > - ret = clk_prepare_enable(qphy->pipe_clk); > - if (ret) { > - dev_err(qmp->dev, "pipe_clk enable failed err=%d\n", ret); > + ret = qcom_qmp_phy_pipe_clk_enable(qphy); > + if (ret) > goto err_reset_lane; > - } > > /* Tx, Rx, and PCS configurations */ > qcom_qmp_phy_configure_lane(tx, cfg->regs, > @@ -5478,7 +5517,7 @@ static int qcom_qmp_phy_power_on(struct phy *phy) > return 0; > > err_disable_pipe_clk: > - clk_disable_unprepare(qphy->pipe_clk); > + qcom_qmp_phy_pipe_clk_disable(qphy); > err_reset_lane: > if (cfg->has_lane_rst) > reset_control_assert(qphy->lane_rst); > @@ -5491,7 +5530,7 @@ static int qcom_qmp_phy_power_off(struct phy *phy) > struct qmp_phy *qphy = phy_get_drvdata(phy); > const struct qmp_phy_cfg *cfg = qphy->cfg; > > - clk_disable_unprepare(qphy->pipe_clk); > + qcom_qmp_phy_pipe_clk_disable(qphy); > > if (cfg->type == PHY_TYPE_DP) { > /* Assert DP PHY power down */ > @@ -5777,6 +5816,8 @@ static int phy_pipe_clk_register(struct qcom_qmp *qmp, struct device_node *np) > if (ret) > return ret; > > + qmp->pipe_clksrc = fixed->hw.clk; > + > ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &fixed->hw); > if (ret) > return ret; > @@ -6091,6 +6132,24 @@ int qcom_qmp_phy_create(struct device *dev, struct device_node *np, int id, > qphy->pipe_clk = NULL; > } > > + /* Get optional pipe clock mux and default reference source clock. */ > + qphy->pipemux_clk = of_clk_get_by_name(np, "mux"); > + if (IS_ERR(qphy->pipemux_clk)) { > + ret = PTR_ERR(qphy->pipemux_clk); > + if (ret == -EPROBE_DEFER) > + return ret; > + > + qphy->pipemux_clk = NULL; > + } else { > + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); > + if (IS_ERR(qphy->piperef_clk)) { > + ret = PTR_ERR(qphy->piperef_clk); > + return dev_err_probe(dev, ret, > + "failed to get lane%d piperef_clk\n", > + id); > + } > + } > + > /* Get lane reset, if any */ > if (cfg->has_lane_rst) { > snprintf(prop_name, sizeof(prop_name), "lane%d", id);
On Thu, Apr 21, 2022 at 02:08:27PM +0300, Dmitry Baryshkov wrote: > On 21/04/2022 13:20, Johan Hovold wrote: > > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > > output generated by the PHY before powering on the PHY and restore the > > default source during power down. > > > > Add support for an optional pipe clock mux which will be reparented to > > the generated pipe clock before powering on the PHY and restored to the > > default reference source on power off. > > > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > > --- > > drivers/phy/qualcomm/phy-qcom-qmp.c | 71 ++++++++++++++++++++++++++--- > > 1 file changed, 65 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c > > index 7d2d1ab061f7..bc6db9670291 100644 > > --- a/drivers/phy/qualcomm/phy-qcom-qmp.c > > +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c > > @@ -3292,6 +3292,8 @@ struct qmp_phy_combo_cfg { > > * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs) > > * @pcs_misc: iomapped memory space for lane's pcs_misc > > * @pipe_clk: pipe clock > > + * @pipemux_clk: pipe clock source mux > > + * @piperef_clk: pipe clock default reference source > > * @index: lane index > > * @qmp: QMP phy to which this lane belongs > > * @lane_rst: lane's reset controller > > @@ -3311,6 +3313,8 @@ struct qmp_phy { > > void __iomem *rx2; > > void __iomem *pcs_misc; > > struct clk *pipe_clk; > > + struct clk *pipemux_clk; > > + struct clk *piperef_clk; > > unsigned int index; > > struct qcom_qmp *qmp; > > struct reset_control *lane_rst; > > @@ -3346,6 +3350,7 @@ struct qcom_qmp { > > void __iomem *dp_com; > > > > struct clk_bulk_data *clks; > > + struct clk *pipe_clksrc; > > Please move this to qmp_phy too. Ok. > > + /* Get optional pipe clock mux and default reference source clock. */ > > + qphy->pipemux_clk = of_clk_get_by_name(np, "mux"); > > + if (IS_ERR(qphy->pipemux_clk)) { > > + ret = PTR_ERR(qphy->pipemux_clk); > > + if (ret == -EPROBE_DEFER) > > + return ret; > > + > > + qphy->pipemux_clk = NULL; > > This makes the driver ignore every possible erorr except -EPROBE_DEFER. > However the driver should behave in quite the oppposite way. Please use > devm_clk_get_optional() instead. It would do that in better way. We'd need to add an optional version of devm_get_clk_from_child() for that due to the questionable "lane" child nodes this driver uses. The above works for an RFC, but testing for -EINVAL and -ENOENT handles a few more theoretical errnos until an optional helper is in place. > Not to mention that this code leaks a refcount on the clock. True, just like the driver has been doing with the pipe clock and lane reset since it was merged. I'll fix that up. > > + } else { > > + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); > > + if (IS_ERR(qphy->piperef_clk)) { > > + ret = PTR_ERR(qphy->piperef_clk); > > + return dev_err_probe(dev, ret, > > + "failed to get lane%d piperef_clk\n", > > + id); > > + } > > + } > > + > > As a second thought. > This needs to be more explicit. If the chipset requires the pipe clock > remuxing, we must fail if the clocks were not provided. So depending on > the qmp instance/property the driver should either use devm_clk_get() > (instead of _optional) or skip this block completely. No, the kernel is not a DT validator (and we have the YAML bindings for that now). > But this will not work with earlier DTS files. So this is not a problem (but if we really wanted to have the driver validate the DT it can be done by updating the compatible strings). Johan
On Fri, 22 Apr 2022 at 13:20, Johan Hovold <johan@kernel.org> wrote: > > On Thu, Apr 21, 2022 at 02:08:27PM +0300, Dmitry Baryshkov wrote: > > On 21/04/2022 13:20, Johan Hovold wrote: > > > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > > > output generated by the PHY before powering on the PHY and restore the > > > default source during power down. > > > > > > Add support for an optional pipe clock mux which will be reparented to > > > the generated pipe clock before powering on the PHY and restored to the > > > default reference source on power off. > > > > > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > > > --- > > > drivers/phy/qualcomm/phy-qcom-qmp.c | 71 ++++++++++++++++++++++++++--- > > > 1 file changed, 65 insertions(+), 6 deletions(-) > > > > > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c > > > index 7d2d1ab061f7..bc6db9670291 100644 > > > --- a/drivers/phy/qualcomm/phy-qcom-qmp.c > > > +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c > > > @@ -3292,6 +3292,8 @@ struct qmp_phy_combo_cfg { > > > * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs) > > > * @pcs_misc: iomapped memory space for lane's pcs_misc > > > * @pipe_clk: pipe clock > > > + * @pipemux_clk: pipe clock source mux > > > + * @piperef_clk: pipe clock default reference source > > > * @index: lane index > > > * @qmp: QMP phy to which this lane belongs > > > * @lane_rst: lane's reset controller > > > @@ -3311,6 +3313,8 @@ struct qmp_phy { > > > void __iomem *rx2; > > > void __iomem *pcs_misc; > > > struct clk *pipe_clk; > > > + struct clk *pipemux_clk; > > > + struct clk *piperef_clk; > > > unsigned int index; > > > struct qcom_qmp *qmp; > > > struct reset_control *lane_rst; > > > @@ -3346,6 +3350,7 @@ struct qcom_qmp { > > > void __iomem *dp_com; > > > > > > struct clk_bulk_data *clks; > > > + struct clk *pipe_clksrc; > > > > Please move this to qmp_phy too. > > Ok. > > > > + /* Get optional pipe clock mux and default reference source clock. */ > > > + qphy->pipemux_clk = of_clk_get_by_name(np, "mux"); > > > + if (IS_ERR(qphy->pipemux_clk)) { > > > + ret = PTR_ERR(qphy->pipemux_clk); > > > + if (ret == -EPROBE_DEFER) > > > + return ret; > > > + > > > + qphy->pipemux_clk = NULL; > > > > This makes the driver ignore every possible erorr except -EPROBE_DEFER. > > However the driver should behave in quite the oppposite way. Please use > > devm_clk_get_optional() instead. It would do that in better way. > > We'd need to add an optional version of devm_get_clk_from_child() for > that due to the questionable "lane" child nodes this driver uses. > > The above works for an RFC, but testing for -EINVAL and -ENOENT handles > a few more theoretical errnos until an optional helper is in place. > > > Not to mention that this code leaks a refcount on the clock. > > True, just like the driver has been doing with the pipe clock and lane > reset since it was merged. I'll fix that up. > > > > + } else { > > > + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); > > > + if (IS_ERR(qphy->piperef_clk)) { > > > + ret = PTR_ERR(qphy->piperef_clk); > > > + return dev_err_probe(dev, ret, > > > + "failed to get lane%d piperef_clk\n", > > > + id); > > > + } > > > + } > > > + > > > > As a second thought. > > This needs to be more explicit. If the chipset requires the pipe clock > > remuxing, we must fail if the clocks were not provided. So depending on > > the qmp instance/property the driver should either use devm_clk_get() > > (instead of _optional) or skip this block completely. > > No, the kernel is not a DT validator (and we have the YAML bindings for > that now). It is not about DT validation. It is about passing a correct DT. The file can come up from the kernel. It can come from the older kernel. OR it can come from the vendor. Or it even might be being a part of firmware flashed into the device. So we can not assume that the DT is correct just because the in-kernel DT passes YAML validation. So, as I wrote, the whole patchset needs much more care about compatibility. > > But this will not work with earlier DTS files. > > So this is not a problem (but if we really wanted to have the driver > validate the DT it can be done by updating the compatible strings). We should not update compatible strings just because the driver changes. Compat strings describe the hardware, not the Linux point of view on it.
On Thu, Apr 21, 2022 at 02:36:05PM +0300, Dmitry Baryshkov wrote: > On 21/04/2022 13:20, Johan Hovold wrote: > > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > > output generated by the PHY before powering on the PHY and restore the > > default source during power down. > > > > Add support for an optional pipe clock mux which will be reparented to > > the generated pipe clock before powering on the PHY and restored to the > > default reference source on power off. > > > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > > --- > > +static int qcom_qmp_phy_pipe_clk_enable(struct qmp_phy *qphy) > > +{ > > + struct qcom_qmp *qmp = qphy->qmp; > > + int ret; > > + > > + ret = clk_set_parent(qphy->pipemux_clk, qmp->pipe_clksrc); > > + if (ret) > > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > > + > > + > > + ret = clk_prepare_enable(qphy->pipe_clk); > > + if (ret) { > > + dev_err(qmp->dev, "failed to enable pipe clock: %d\n", ret); > > + goto err_restore_parent; > > + } > > So, what you do here is you manually set the parent of > GCC_PCIE_1_PIPE_CLK_SRC to PHY pipe clock right before enabling > GCC_PCIE_1_PIPE_CLK and set it back to XO after disabling > GCC_PCIE_1_PIPE_CLK. > > My proposal is doing exactly the same, but doing that automatically > through the clock infrastructure. After removing pipe_clock handling > from pcie driver itself, we can be sure that nobody is playing dirty > tricks around the pipe_clock. Yes, the end result is similar, but I believe handling it explicitly in the driver is preferred for a number of reasons that I've already mentioned. Not least because the mux needs to be updated when the PHY is powered on, not when the GCC pipe clock is ungated. In practise, powering on the PHY and ungating the clock happen to coincide in time because only the PHY driver will use the GCC pipe clock, but conceptually they are unrelated (and as the GDSC hang shows, something in the system appears to be ungating the clock while the PHY is powered off). The QMP PHY driver implementation is much more straight forward and easier to reason about than having the mux implementation spread out over multiple clock drivers where it's not clear at all what is really going on or why (and even debugfs will give you a false view of the clock tree state). > > + > > + return 0; > > + > > +err_restore_parent: > > + clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > > + > > + return ret; > > +} > > + > > +static void qcom_qmp_phy_pipe_clk_disable(struct qmp_phy *qphy) > > +{ > > + struct qcom_qmp *qmp = qphy->qmp; > > + int ret; > > + > > + clk_disable_unprepare(qphy->pipe_clk); > > + > > + ret = clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > > + if (ret) > > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > > +} > > + Johan
[ Again, please trim unnecessary context from your replies. ] On Fri, Apr 22, 2022 at 01:35:01PM +0300, Dmitry Baryshkov wrote: > On Fri, 22 Apr 2022 at 13:20, Johan Hovold <johan@kernel.org> wrote: > > > > On Thu, Apr 21, 2022 at 02:08:27PM +0300, Dmitry Baryshkov wrote: > > > On 21/04/2022 13:20, Johan Hovold wrote: > > > > + /* Get optional pipe clock mux and default reference source clock. */ > > > > + qphy->pipemux_clk = of_clk_get_by_name(np, "mux"); > > > > + if (IS_ERR(qphy->pipemux_clk)) { > > > > + ret = PTR_ERR(qphy->pipemux_clk); > > > > + if (ret == -EPROBE_DEFER) > > > > + return ret; > > > > + > > > > + qphy->pipemux_clk = NULL; > > > > + } else { > > > > + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); > > > > + if (IS_ERR(qphy->piperef_clk)) { > > > > + ret = PTR_ERR(qphy->piperef_clk); > > > > + return dev_err_probe(dev, ret, > > > > + "failed to get lane%d piperef_clk\n", > > > > + id); > > > > + } > > > > + } > > > > + > > > > > > As a second thought. > > > This needs to be more explicit. If the chipset requires the pipe clock > > > remuxing, we must fail if the clocks were not provided. So depending on > > > the qmp instance/property the driver should either use devm_clk_get() > > > (instead of _optional) or skip this block completely. > > > > No, the kernel is not a DT validator (and we have the YAML bindings for > > that now). > > It is not about DT validation. It is about passing a correct DT. Heh. That's the same thing. > The file can come up from the kernel. It can come from the older > kernel. OR it can come from the vendor. Or it even might be being a > part of firmware flashed into the device. So we can not assume that > the DT is correct just because the in-kernel DT passes YAML > validation. Again, no. The kernel does not need to implement DT validation and can assume that the DT describes the hardware accurately. If the DT says there's a mux, the driver can use it. If there's no mux in DT, the driver can assume it isn't there. The only thing that complicates things here is the sc7280 dts which has been released in 5.16. We don't care about Qualcomm's kernels and dts. > So, as I wrote, the whole patchset needs much more care about compatibility. > > > > But this will not work with earlier DTS files. > > > > So this is not a problem (but if we really wanted to have the driver > > validate the DT it can be done by updating the compatible strings). > > We should not update compatible strings just because the driver > changes. Compat strings describe the hardware, not the Linux point of > view on it. We can, it's a documented practise in case a binding needs to be updated in an incompatible way: https://www.kernel.org/doc/html/latest/devicetree/bindings/ABI.html But I don't think it'll be needed here. Johan
On Thu 21 Apr 03:20 PDT 2022, Johan Hovold wrote: > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > output generated by the PHY before powering on the PHY and restore the > default source during power down. > > Add support for an optional pipe clock mux which will be reparented to > the generated pipe clock before powering on the PHY and restored to the > default reference source on power off. > After considering this for a while, I have two objections to doing this explicitly: 1) The QMP block is fed &gcc_pcie_N_pipe_clk (and on sc8280xp) gcc_pcie_N_pipediv2_clk. But neither of these clocks are the mux, so what this patch (and the existing muxing logic in the controller) does is to poke into gcc "internals". 2) The actual reason for the mux dance is that toggling the associated GDSC without a valid parent of this clock would cause the clock to lock up and GDSC transition to time out. This property is shared with a wide range of other clocks (so far we have 84 users of clk_rcg2_shared_ops on sc8280xp). It would be nice if clk_summary would represent the real state of these clocks, but unfortunately I don't think the state matches reality with this approach either. E.g. we prepare/enable the pipe clock before setting QPHY_POWER_DOWN_CONTROL, during this time there's shouldn't be any pipe clock coming out of the PHY... Regards, Bjorn > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> > --- > drivers/phy/qualcomm/phy-qcom-qmp.c | 71 ++++++++++++++++++++++++++--- > 1 file changed, 65 insertions(+), 6 deletions(-) > > diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c > index 7d2d1ab061f7..bc6db9670291 100644 > --- a/drivers/phy/qualcomm/phy-qcom-qmp.c > +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c > @@ -3292,6 +3292,8 @@ struct qmp_phy_combo_cfg { > * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs) > * @pcs_misc: iomapped memory space for lane's pcs_misc > * @pipe_clk: pipe clock > + * @pipemux_clk: pipe clock source mux > + * @piperef_clk: pipe clock default reference source > * @index: lane index > * @qmp: QMP phy to which this lane belongs > * @lane_rst: lane's reset controller > @@ -3311,6 +3313,8 @@ struct qmp_phy { > void __iomem *rx2; > void __iomem *pcs_misc; > struct clk *pipe_clk; > + struct clk *pipemux_clk; > + struct clk *piperef_clk; > unsigned int index; > struct qcom_qmp *qmp; > struct reset_control *lane_rst; > @@ -3346,6 +3350,7 @@ struct qcom_qmp { > void __iomem *dp_com; > > struct clk_bulk_data *clks; > + struct clk *pipe_clksrc; > struct reset_control **resets; > struct regulator_bulk_data *vregs; > > @@ -5355,6 +5360,42 @@ static int qcom_qmp_phy_init(struct phy *phy) > return 0; > } > > +static int qcom_qmp_phy_pipe_clk_enable(struct qmp_phy *qphy) > +{ > + struct qcom_qmp *qmp = qphy->qmp; > + int ret; > + > + ret = clk_set_parent(qphy->pipemux_clk, qmp->pipe_clksrc); > + if (ret) > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > + > + > + ret = clk_prepare_enable(qphy->pipe_clk); > + if (ret) { > + dev_err(qmp->dev, "failed to enable pipe clock: %d\n", ret); > + goto err_restore_parent; > + } > + > + return 0; > + > +err_restore_parent: > + clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > + > + return ret; > +} > + > +static void qcom_qmp_phy_pipe_clk_disable(struct qmp_phy *qphy) > +{ > + struct qcom_qmp *qmp = qphy->qmp; > + int ret; > + > + clk_disable_unprepare(qphy->pipe_clk); > + > + ret = clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); > + if (ret) > + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); > +} > + > static int qcom_qmp_phy_power_on(struct phy *phy) > { > struct qmp_phy *qphy = phy_get_drvdata(phy); > @@ -5379,11 +5420,9 @@ static int qcom_qmp_phy_power_on(struct phy *phy) > } > } > > - ret = clk_prepare_enable(qphy->pipe_clk); > - if (ret) { > - dev_err(qmp->dev, "pipe_clk enable failed err=%d\n", ret); > + ret = qcom_qmp_phy_pipe_clk_enable(qphy); > + if (ret) > goto err_reset_lane; > - } > > /* Tx, Rx, and PCS configurations */ > qcom_qmp_phy_configure_lane(tx, cfg->regs, > @@ -5478,7 +5517,7 @@ static int qcom_qmp_phy_power_on(struct phy *phy) > return 0; > > err_disable_pipe_clk: > - clk_disable_unprepare(qphy->pipe_clk); > + qcom_qmp_phy_pipe_clk_disable(qphy); > err_reset_lane: > if (cfg->has_lane_rst) > reset_control_assert(qphy->lane_rst); > @@ -5491,7 +5530,7 @@ static int qcom_qmp_phy_power_off(struct phy *phy) > struct qmp_phy *qphy = phy_get_drvdata(phy); > const struct qmp_phy_cfg *cfg = qphy->cfg; > > - clk_disable_unprepare(qphy->pipe_clk); > + qcom_qmp_phy_pipe_clk_disable(qphy); > > if (cfg->type == PHY_TYPE_DP) { > /* Assert DP PHY power down */ > @@ -5777,6 +5816,8 @@ static int phy_pipe_clk_register(struct qcom_qmp *qmp, struct device_node *np) > if (ret) > return ret; > > + qmp->pipe_clksrc = fixed->hw.clk; > + > ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &fixed->hw); > if (ret) > return ret; > @@ -6091,6 +6132,24 @@ int qcom_qmp_phy_create(struct device *dev, struct device_node *np, int id, > qphy->pipe_clk = NULL; > } > > + /* Get optional pipe clock mux and default reference source clock. */ > + qphy->pipemux_clk = of_clk_get_by_name(np, "mux"); > + if (IS_ERR(qphy->pipemux_clk)) { > + ret = PTR_ERR(qphy->pipemux_clk); > + if (ret == -EPROBE_DEFER) > + return ret; > + > + qphy->pipemux_clk = NULL; > + } else { > + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); > + if (IS_ERR(qphy->piperef_clk)) { > + ret = PTR_ERR(qphy->piperef_clk); > + return dev_err_probe(dev, ret, > + "failed to get lane%d piperef_clk\n", > + id); > + } > + } > + > /* Get lane reset, if any */ > if (cfg->has_lane_rst) { > snprintf(prop_name, sizeof(prop_name), "lane%d", id); > -- > 2.35.1 >
On Fri, Apr 22, 2022 at 5:35 AM Dmitry Baryshkov <dmitry.baryshkov@linaro.org> wrote: > > On Fri, 22 Apr 2022 at 13:20, Johan Hovold <johan@kernel.org> wrote: > > > > On Thu, Apr 21, 2022 at 02:08:27PM +0300, Dmitry Baryshkov wrote: > > > On 21/04/2022 13:20, Johan Hovold wrote: > > > > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > > > > output generated by the PHY before powering on the PHY and restore the > > > > default source during power down. > > > > > > > > Add support for an optional pipe clock mux which will be reparented to > > > > the generated pipe clock before powering on the PHY and restored to the > > > > default reference source on power off. > > > > > > > > Signed-off-by: Johan Hovold <johan+linaro@kernel.org> [...] > > > > + } else { > > > > + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); > > > > + if (IS_ERR(qphy->piperef_clk)) { > > > > + ret = PTR_ERR(qphy->piperef_clk); > > > > + return dev_err_probe(dev, ret, > > > > + "failed to get lane%d piperef_clk\n", > > > > + id); > > > > + } > > > > + } > > > > + > > > > > > As a second thought. > > > This needs to be more explicit. If the chipset requires the pipe clock > > > remuxing, we must fail if the clocks were not provided. So depending on > > > the qmp instance/property the driver should either use devm_clk_get() > > > (instead of _optional) or skip this block completely. > > > > No, the kernel is not a DT validator (and we have the YAML bindings for > > that now). > > It is not about DT validation. It is about passing a correct DT. The > file can come up from the kernel. It can come from the older kernel. > OR it can come from the vendor. Or it even might be being a part of > firmware flashed into the device. As of dtschema 2022.03, validation of dtb's from firmware (or anywhere else) is supported. Of course, as the old saying goes, if it's not upstream, it doesn't exist. We can't control what vendors do in their DTs. > So we can not assume that the DT is correct just because the in-kernel > DT passes YAML validation. I agree with Johan on this. In terms of ensuring correctness, the kernel does a horrible job. It never will be as long as it is done in ad hoc code. > So, as I wrote, the whole patchset needs much more care about compatibility. > > > > But this will not work with earlier DTS files. > > > > So this is not a problem (but if we really wanted to have the driver > > validate the DT it can be done by updating the compatible strings). > > We should not update compatible strings just because the driver > changes. Compat strings describe the hardware, not the Linux point of > view on it. Yes and no. It is the OS/client view of the h/w. If a binding is deemed horribly broken we could do a new compatible string and binding. That's not something we want to be doing frequently though. Rob
On Thu, Apr 28, 2022 at 06:11:44AM -0700, Bjorn Andersson wrote: > On Thu 21 Apr 03:20 PDT 2022, Johan Hovold wrote: > > > Some QMP PHYs need to remux to their pipe clock input to the pipe clock > > output generated by the PHY before powering on the PHY and restore the > > default source during power down. > > > > Add support for an optional pipe clock mux which will be reparented to > > the generated pipe clock before powering on the PHY and restored to the > > default reference source on power off. > > > > After considering this for a while, I have two objections to doing this > explicitly: > > 1) The QMP block is fed &gcc_pcie_N_pipe_clk (and on sc8280xp) > gcc_pcie_N_pipediv2_clk. But neither of these clocks are the mux, so > what this patch (and the existing muxing logic in the controller) does > is to poke into gcc "internals". I agree that this is perhaps the strongest argument against describing the mux in DT (as is also currently done for sc7280). > 2) The actual reason for the mux dance is that toggling the associated > GDSC without a valid parent of this clock would cause the clock to lock > up and GDSC transition to time out. This property is shared with a wide > range of other clocks (so far we have 84 users of clk_rcg2_shared_ops on > sc8280xp). Right, but the situation with rcg2 is a little different. From what I gather the problem there is that some downstream clock could have been enabled by some other part of the system behind the kernel's back and then things go wrong when the kernel configures the clock. Here it is the kernel that controls the source of the pipe clock mux (the PHY PLL) and knows when the source is valid (and the PHY is both provider and consumer of the pipe clock). For rcg2, there's no choice but to work around the hardware in the clock driver, while for QMP the PHY power sequences could be made explicit in the driver: clk_prepare_enable(pipe); clk_set_parent(pipe_src, pll); start_pll(); stop_pll(); clk_set_parent(pipe_src, xo); clk_disable_unprepare(pipe); Note that with the above sequences it would be possible to drop the pipe clock BRANCH_HALT_SKIP flag, which is only there in the clock driver because of the how the PHY works (i.e. that the pipe clock must be ungated before the PLL is started). (This wouldn't be possible with a pipe-mux implementation in the clock driver since the parent mux would be enabled before the child pipe clock.) But sure, the requirement to restore XO to prevent a later GDSC hang has little to do with the PHY. > It would be nice if clk_summary would represent the real state of these > clocks, but unfortunately I don't think the state matches reality with > this approach either. > > E.g. we prepare/enable the pipe clock before setting > QPHY_POWER_DOWN_CONTROL, during this time there's shouldn't be any pipe > clock coming out of the PHY... Right, there's a small window there where the source is still off (due to hardware requirements), but at least the topology is always reported correctly, which is really useful when dealing with boot handover. I have an sc8280xp here where the boot firmware leaves the pipe clock muxed in despite the GDSC being disabled. Fortunately, it doesn't seem to trigger the lockup when toggling the GDSC as it does on an sa8540p. My concerns are otherwise mostly related to the implementation of the safe-mux (e.g. ad-hoc, missing locking) and can probably be addressed. As an example, with the current implementation it is not possible to use an assigned clock parent in DT to make sure that the XO source is selected before toggling the GDSC. The muxing doesn't happen until the pipe clock is enabled, which is much too late in case the boot firmware left the pipe clock muxed in, and when enabling the pipe clock you really want the PHY PLL as source and not the cached XO. Can you still drop the current safe-mux patches from your tree or would they need to be fixed up incrementally? I think you merged v2, but there's already a v3 out (addressing the hardcoded mux configuration values). Johan
diff --git a/drivers/phy/qualcomm/phy-qcom-qmp.c b/drivers/phy/qualcomm/phy-qcom-qmp.c index 7d2d1ab061f7..bc6db9670291 100644 --- a/drivers/phy/qualcomm/phy-qcom-qmp.c +++ b/drivers/phy/qualcomm/phy-qcom-qmp.c @@ -3292,6 +3292,8 @@ struct qmp_phy_combo_cfg { * @rx2: iomapped memory space for second lane's rx (in dual lane PHYs) * @pcs_misc: iomapped memory space for lane's pcs_misc * @pipe_clk: pipe clock + * @pipemux_clk: pipe clock source mux + * @piperef_clk: pipe clock default reference source * @index: lane index * @qmp: QMP phy to which this lane belongs * @lane_rst: lane's reset controller @@ -3311,6 +3313,8 @@ struct qmp_phy { void __iomem *rx2; void __iomem *pcs_misc; struct clk *pipe_clk; + struct clk *pipemux_clk; + struct clk *piperef_clk; unsigned int index; struct qcom_qmp *qmp; struct reset_control *lane_rst; @@ -3346,6 +3350,7 @@ struct qcom_qmp { void __iomem *dp_com; struct clk_bulk_data *clks; + struct clk *pipe_clksrc; struct reset_control **resets; struct regulator_bulk_data *vregs; @@ -5355,6 +5360,42 @@ static int qcom_qmp_phy_init(struct phy *phy) return 0; } +static int qcom_qmp_phy_pipe_clk_enable(struct qmp_phy *qphy) +{ + struct qcom_qmp *qmp = qphy->qmp; + int ret; + + ret = clk_set_parent(qphy->pipemux_clk, qmp->pipe_clksrc); + if (ret) + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); + + + ret = clk_prepare_enable(qphy->pipe_clk); + if (ret) { + dev_err(qmp->dev, "failed to enable pipe clock: %d\n", ret); + goto err_restore_parent; + } + + return 0; + +err_restore_parent: + clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); + + return ret; +} + +static void qcom_qmp_phy_pipe_clk_disable(struct qmp_phy *qphy) +{ + struct qcom_qmp *qmp = qphy->qmp; + int ret; + + clk_disable_unprepare(qphy->pipe_clk); + + ret = clk_set_parent(qphy->pipemux_clk, qphy->piperef_clk); + if (ret) + dev_err(qmp->dev, "failed to reparent pipe clock: %d\n", ret); +} + static int qcom_qmp_phy_power_on(struct phy *phy) { struct qmp_phy *qphy = phy_get_drvdata(phy); @@ -5379,11 +5420,9 @@ static int qcom_qmp_phy_power_on(struct phy *phy) } } - ret = clk_prepare_enable(qphy->pipe_clk); - if (ret) { - dev_err(qmp->dev, "pipe_clk enable failed err=%d\n", ret); + ret = qcom_qmp_phy_pipe_clk_enable(qphy); + if (ret) goto err_reset_lane; - } /* Tx, Rx, and PCS configurations */ qcom_qmp_phy_configure_lane(tx, cfg->regs, @@ -5478,7 +5517,7 @@ static int qcom_qmp_phy_power_on(struct phy *phy) return 0; err_disable_pipe_clk: - clk_disable_unprepare(qphy->pipe_clk); + qcom_qmp_phy_pipe_clk_disable(qphy); err_reset_lane: if (cfg->has_lane_rst) reset_control_assert(qphy->lane_rst); @@ -5491,7 +5530,7 @@ static int qcom_qmp_phy_power_off(struct phy *phy) struct qmp_phy *qphy = phy_get_drvdata(phy); const struct qmp_phy_cfg *cfg = qphy->cfg; - clk_disable_unprepare(qphy->pipe_clk); + qcom_qmp_phy_pipe_clk_disable(qphy); if (cfg->type == PHY_TYPE_DP) { /* Assert DP PHY power down */ @@ -5777,6 +5816,8 @@ static int phy_pipe_clk_register(struct qcom_qmp *qmp, struct device_node *np) if (ret) return ret; + qmp->pipe_clksrc = fixed->hw.clk; + ret = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &fixed->hw); if (ret) return ret; @@ -6091,6 +6132,24 @@ int qcom_qmp_phy_create(struct device *dev, struct device_node *np, int id, qphy->pipe_clk = NULL; } + /* Get optional pipe clock mux and default reference source clock. */ + qphy->pipemux_clk = of_clk_get_by_name(np, "mux"); + if (IS_ERR(qphy->pipemux_clk)) { + ret = PTR_ERR(qphy->pipemux_clk); + if (ret == -EPROBE_DEFER) + return ret; + + qphy->pipemux_clk = NULL; + } else { + qphy->piperef_clk = of_clk_get_by_name(np, "ref"); + if (IS_ERR(qphy->piperef_clk)) { + ret = PTR_ERR(qphy->piperef_clk); + return dev_err_probe(dev, ret, + "failed to get lane%d piperef_clk\n", + id); + } + } + /* Get lane reset, if any */ if (cfg->has_lane_rst) { snprintf(prop_name, sizeof(prop_name), "lane%d", id);
Some QMP PHYs need to remux to their pipe clock input to the pipe clock output generated by the PHY before powering on the PHY and restore the default source during power down. Add support for an optional pipe clock mux which will be reparented to the generated pipe clock before powering on the PHY and restored to the default reference source on power off. Signed-off-by: Johan Hovold <johan+linaro@kernel.org> --- drivers/phy/qualcomm/phy-qcom-qmp.c | 71 ++++++++++++++++++++++++++--- 1 file changed, 65 insertions(+), 6 deletions(-)