| Message ID | 20211123162508.153711-1-bjorn.andersson@linaro.org (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | [v2] clk: qcom: clk-alpha-pll: Don't reconfigure running Trion | expand |
Hey Bjorn, On Tue, 23 Nov 2021 at 17:23, Bjorn Andersson <bjorn.andersson@linaro.org> wrote: > > In the event that the bootloader has configured the Trion PLL as source > for the display clocks, e.g. for the continuous splashscreen, then there > will also be RCGs that are clocked by this instance. > > Reconfiguring, and in particular disabling the output of, the PLL will > cause issues for these downstream RCGs and has been shown to prevent > them from being re-parented. > > Follow downstream and skip configuration if it's determined that the PLL > is already running. > > Fixes: 59128c20a6a9 ("clk: qcom: clk-alpha-pll: Add support for controlling Lucid PLLs") > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> > --- > > Changes since v1: > - Forgot to commit the last minute s/pr_dbg/pr_debug/ > > drivers/clk/qcom/clk-alpha-pll.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c > index eaedcceb766f..8f65b9bdafce 100644 > --- a/drivers/clk/qcom/clk-alpha-pll.c > +++ b/drivers/clk/qcom/clk-alpha-pll.c > @@ -1429,6 +1429,15 @@ EXPORT_SYMBOL_GPL(clk_alpha_pll_postdiv_fabia_ops); > void clk_trion_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap, > const struct alpha_pll_config *config) > { > + /* > + * If the bootloader left the PLL enabled it's likely that there are > + * RCGs that will lock up if we disable the PLL below. > + */ > + if (trion_pll_is_enabled(pll, regmap)) { > + pr_debug("Trion PLL is already enabled, skipping configuration\n"); > + return; > + } > + > clk_alpha_pll_write_config(regmap, PLL_L_VAL(pll), config->l); > regmap_write(regmap, PLL_CAL_L_VAL(pll), TRION_PLL_CAL_VAL); > clk_alpha_pll_write_config(regmap, PLL_ALPHA_VAL(pll), config->alpha); > -- > 2.33.1 This resolves an issue I was seeing related to clocks not being able to get updated. Reviewed-by: Robert Foss <robert.foss@linaro.org>
On 23-11-21, 08:25, Bjorn Andersson wrote: > In the event that the bootloader has configured the Trion PLL as source > for the display clocks, e.g. for the continuous splashscreen, then there > will also be RCGs that are clocked by this instance. > > Reconfiguring, and in particular disabling the output of, the PLL will > cause issues for these downstream RCGs and has been shown to prevent > them from being re-parented. > > Follow downstream and skip configuration if it's determined that the PLL > is already running. Reviewed-by: Vinod Koul <vkoul@kernel.org>
Quoting Bjorn Andersson (2021-11-23 08:25:08) > In the event that the bootloader has configured the Trion PLL as source > for the display clocks, e.g. for the continuous splashscreen, then there > will also be RCGs that are clocked by this instance. > > Reconfiguring, and in particular disabling the output of, the PLL will > cause issues for these downstream RCGs and has been shown to prevent > them from being re-parented. > > Follow downstream and skip configuration if it's determined that the PLL > is already running. > > Fixes: 59128c20a6a9 ("clk: qcom: clk-alpha-pll: Add support for controlling Lucid PLLs") > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> > --- Applied to clk-fixes
diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c index eaedcceb766f..8f65b9bdafce 100644 --- a/drivers/clk/qcom/clk-alpha-pll.c +++ b/drivers/clk/qcom/clk-alpha-pll.c @@ -1429,6 +1429,15 @@ EXPORT_SYMBOL_GPL(clk_alpha_pll_postdiv_fabia_ops); void clk_trion_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap, const struct alpha_pll_config *config) { + /* + * If the bootloader left the PLL enabled it's likely that there are + * RCGs that will lock up if we disable the PLL below. + */ + if (trion_pll_is_enabled(pll, regmap)) { + pr_debug("Trion PLL is already enabled, skipping configuration\n"); + return; + } + clk_alpha_pll_write_config(regmap, PLL_L_VAL(pll), config->l); regmap_write(regmap, PLL_CAL_L_VAL(pll), TRION_PLL_CAL_VAL); clk_alpha_pll_write_config(regmap, PLL_ALPHA_VAL(pll), config->alpha);
In the event that the bootloader has configured the Trion PLL as source for the display clocks, e.g. for the continuous splashscreen, then there will also be RCGs that are clocked by this instance. Reconfiguring, and in particular disabling the output of, the PLL will cause issues for these downstream RCGs and has been shown to prevent them from being re-parented. Follow downstream and skip configuration if it's determined that the PLL is already running. Fixes: 59128c20a6a9 ("clk: qcom: clk-alpha-pll: Add support for controlling Lucid PLLs") Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> --- Changes since v1: - Forgot to commit the last minute s/pr_dbg/pr_debug/ drivers/clk/qcom/clk-alpha-pll.c | 9 +++++++++ 1 file changed, 9 insertions(+)