| Message ID | 20201214092048.v5.2.I7564620993acd4baa63fa0e3925ca879a86d3ee3@changeid (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | f16c8fd4449efb4441272af6102e55523b15a7ad |
| Headers | show |
| Series | [v5,1/2] mmc: sdhci-msm: Warn about overclocking SD/MMC | expand |
On 14/12/20 7:21 pm, Douglas Anderson wrote: > The MSM SDHCI driver always set the "actual_clock" field to 0. It had > a comment about it not being needed because we weren't using the > standard SDHCI divider mechanism and we'd just fallback to > "host->clock". However, it's still better to provide the actual > clock. Why? > > 1. It will make timeout calculations slightly better. On one system I > have, the eMMC requets 200 MHz (for HS400-ES) but actually gets 192 > MHz. These are close, but why not get the more accurate one. > > 2. If things are seriously off in the clock driver and it's missing > rates or picking the wrong rate (maybe it's rounding up instead of > down), this will make it much more obvious what's going on. > > NOTE: we have to be a little careful here because the "actual_clock" > field shouldn't include the multiplier that sdhci-msm needs > internally. > > Suggested-by: Adrian Hunter <adrian.hunter@intel.com> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Acked-by: Adrian Hunter <adrian.hunter@intel.com> > --- > > Changes in v5: > - Remove unused clock parameter. > - Add a comment that we're stashing the requested rate. > > Changes in v4: > - ("mmc: sdhci-msm: Actually set the actual clock") new for v4. > > drivers/mmc/host/sdhci-msm.c | 35 ++++++++++++++++------------------- > 1 file changed, 16 insertions(+), 19 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c > index 50beb407dbe9..f5669dc858d0 100644 > --- a/drivers/mmc/host/sdhci-msm.c > +++ b/drivers/mmc/host/sdhci-msm.c > @@ -328,8 +328,7 @@ static void sdhci_msm_v5_variant_writel_relaxed(u32 val, > writel_relaxed(val, host->ioaddr + offset); > } > > -static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, > - unsigned int clock) > +static unsigned int msm_get_clock_mult_for_bus_mode(struct sdhci_host *host) > { > struct mmc_ios ios = host->mmc->ios; > /* > @@ -342,8 +341,8 @@ static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, > ios.timing == MMC_TIMING_MMC_DDR52 || > ios.timing == MMC_TIMING_MMC_HS400 || > host->flags & SDHCI_HS400_TUNING) > - clock *= 2; > - return clock; > + return 2; > + return 1; > } > > static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > @@ -354,14 +353,16 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > struct mmc_ios curr_ios = host->mmc->ios; > struct clk *core_clk = msm_host->bulk_clks[0].clk; > unsigned long achieved_rate; > + unsigned int desired_rate; > + unsigned int mult; > int rc; > > - clock = msm_get_clock_rate_for_bus_mode(host, clock); > - rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), clock); > + mult = msm_get_clock_mult_for_bus_mode(host); > + desired_rate = clock * mult; > + rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), desired_rate); > if (rc) { > pr_err("%s: Failed to set clock at rate %u at timing %d\n", > - mmc_hostname(host->mmc), clock, > - curr_ios.timing); > + mmc_hostname(host->mmc), desired_rate, curr_ios.timing); > return; > } > > @@ -371,11 +372,14 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > * encounter it. > */ > achieved_rate = clk_get_rate(core_clk); > - if (achieved_rate > clock) > + if (achieved_rate > desired_rate) > pr_warn("%s: Card appears overclocked; req %u Hz, actual %lu Hz\n", > - mmc_hostname(host->mmc), clock, achieved_rate); > + mmc_hostname(host->mmc), desired_rate, achieved_rate); > + host->mmc->actual_clock = achieved_rate / mult; > + > + /* Stash the rate we requested to use in sdhci_msm_runtime_resume() */ > + msm_host->clk_rate = desired_rate; > > - msm_host->clk_rate = clock; > pr_debug("%s: Setting clock at rate %lu at timing %d\n", > mmc_hostname(host->mmc), achieved_rate, curr_ios.timing); > } > @@ -1756,13 +1760,6 @@ static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host) > static void __sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) > { > u16 clk; > - /* > - * Keep actual_clock as zero - > - * - since there is no divider used so no need of having actual_clock. > - * - MSM controller uses SDCLK for data timeout calculation. If > - * actual_clock is zero, host->clock is taken for calculation. > - */ > - host->mmc->actual_clock = 0; > > sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL); > > @@ -1785,7 +1782,7 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) > struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host); > > if (!clock) { > - msm_host->clk_rate = clock; > + host->mmc->actual_clock = msm_host->clk_rate = 0; > goto out; > } > >
On 12/14/2020 10:51 PM, Douglas Anderson wrote: > The MSM SDHCI driver always set the "actual_clock" field to 0. It had > a comment about it not being needed because we weren't using the > standard SDHCI divider mechanism and we'd just fallback to > "host->clock". However, it's still better to provide the actual > clock. Why? > > 1. It will make timeout calculations slightly better. On one system I > have, the eMMC requets 200 MHz (for HS400-ES) but actually gets 192 > MHz. These are close, but why not get the more accurate one. > > 2. If things are seriously off in the clock driver and it's missing > rates or picking the wrong rate (maybe it's rounding up instead of > down), this will make it much more obvious what's going on. > > NOTE: we have to be a little careful here because the "actual_clock" > field shouldn't include the multiplier that sdhci-msm needs > internally. > > Suggested-by: Adrian Hunter <adrian.hunter@intel.com> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Reviewed-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org> > --- > > Changes in v5: > - Remove unused clock parameter. > - Add a comment that we're stashing the requested rate. > > Changes in v4: > - ("mmc: sdhci-msm: Actually set the actual clock") new for v4. > > drivers/mmc/host/sdhci-msm.c | 35 ++++++++++++++++------------------- > 1 file changed, 16 insertions(+), 19 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c > index 50beb407dbe9..f5669dc858d0 100644 > --- a/drivers/mmc/host/sdhci-msm.c > +++ b/drivers/mmc/host/sdhci-msm.c > @@ -328,8 +328,7 @@ static void sdhci_msm_v5_variant_writel_relaxed(u32 val, > writel_relaxed(val, host->ioaddr + offset); > } > > -static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, > - unsigned int clock) > +static unsigned int msm_get_clock_mult_for_bus_mode(struct sdhci_host *host) > { > struct mmc_ios ios = host->mmc->ios; > /* > @@ -342,8 +341,8 @@ static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, > ios.timing == MMC_TIMING_MMC_DDR52 || > ios.timing == MMC_TIMING_MMC_HS400 || > host->flags & SDHCI_HS400_TUNING) > - clock *= 2; > - return clock; > + return 2; > + return 1; > } > > static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > @@ -354,14 +353,16 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > struct mmc_ios curr_ios = host->mmc->ios; > struct clk *core_clk = msm_host->bulk_clks[0].clk; > unsigned long achieved_rate; > + unsigned int desired_rate; > + unsigned int mult; > int rc; > > - clock = msm_get_clock_rate_for_bus_mode(host, clock); > - rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), clock); > + mult = msm_get_clock_mult_for_bus_mode(host); > + desired_rate = clock * mult; > + rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), desired_rate); > if (rc) { > pr_err("%s: Failed to set clock at rate %u at timing %d\n", > - mmc_hostname(host->mmc), clock, > - curr_ios.timing); > + mmc_hostname(host->mmc), desired_rate, curr_ios.timing); > return; > } > > @@ -371,11 +372,14 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > * encounter it. > */ > achieved_rate = clk_get_rate(core_clk); > - if (achieved_rate > clock) > + if (achieved_rate > desired_rate) > pr_warn("%s: Card appears overclocked; req %u Hz, actual %lu Hz\n", > - mmc_hostname(host->mmc), clock, achieved_rate); > + mmc_hostname(host->mmc), desired_rate, achieved_rate); > + host->mmc->actual_clock = achieved_rate / mult; > + > + /* Stash the rate we requested to use in sdhci_msm_runtime_resume() */ > + msm_host->clk_rate = desired_rate; > > - msm_host->clk_rate = clock; > pr_debug("%s: Setting clock at rate %lu at timing %d\n", > mmc_hostname(host->mmc), achieved_rate, curr_ios.timing); > } > @@ -1756,13 +1760,6 @@ static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host) > static void __sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) > { > u16 clk; > - /* > - * Keep actual_clock as zero - > - * - since there is no divider used so no need of having actual_clock. > - * - MSM controller uses SDCLK for data timeout calculation. If > - * actual_clock is zero, host->clock is taken for calculation. > - */ > - host->mmc->actual_clock = 0; > > sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL); > > @@ -1785,7 +1782,7 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) > struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host); > > if (!clock) { > - msm_host->clk_rate = clock; > + host->mmc->actual_clock = msm_host->clk_rate = 0; > goto out; > } >
On Mon, 14 Dec 2020 at 18:23, Douglas Anderson <dianders@chromium.org> wrote: > > The MSM SDHCI driver always set the "actual_clock" field to 0. It had > a comment about it not being needed because we weren't using the > standard SDHCI divider mechanism and we'd just fallback to > "host->clock". However, it's still better to provide the actual > clock. Why? > > 1. It will make timeout calculations slightly better. On one system I > have, the eMMC requets 200 MHz (for HS400-ES) but actually gets 192 > MHz. These are close, but why not get the more accurate one. > > 2. If things are seriously off in the clock driver and it's missing > rates or picking the wrong rate (maybe it's rounding up instead of > down), this will make it much more obvious what's going on. > > NOTE: we have to be a little careful here because the "actual_clock" > field shouldn't include the multiplier that sdhci-msm needs > internally. > > Suggested-by: Adrian Hunter <adrian.hunter@intel.com> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Applied for next, thanks! Kind regards Uffe > --- > > Changes in v5: > - Remove unused clock parameter. > - Add a comment that we're stashing the requested rate. > > Changes in v4: > - ("mmc: sdhci-msm: Actually set the actual clock") new for v4. > > drivers/mmc/host/sdhci-msm.c | 35 ++++++++++++++++------------------- > 1 file changed, 16 insertions(+), 19 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c > index 50beb407dbe9..f5669dc858d0 100644 > --- a/drivers/mmc/host/sdhci-msm.c > +++ b/drivers/mmc/host/sdhci-msm.c > @@ -328,8 +328,7 @@ static void sdhci_msm_v5_variant_writel_relaxed(u32 val, > writel_relaxed(val, host->ioaddr + offset); > } > > -static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, > - unsigned int clock) > +static unsigned int msm_get_clock_mult_for_bus_mode(struct sdhci_host *host) > { > struct mmc_ios ios = host->mmc->ios; > /* > @@ -342,8 +341,8 @@ static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, > ios.timing == MMC_TIMING_MMC_DDR52 || > ios.timing == MMC_TIMING_MMC_HS400 || > host->flags & SDHCI_HS400_TUNING) > - clock *= 2; > - return clock; > + return 2; > + return 1; > } > > static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > @@ -354,14 +353,16 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > struct mmc_ios curr_ios = host->mmc->ios; > struct clk *core_clk = msm_host->bulk_clks[0].clk; > unsigned long achieved_rate; > + unsigned int desired_rate; > + unsigned int mult; > int rc; > > - clock = msm_get_clock_rate_for_bus_mode(host, clock); > - rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), clock); > + mult = msm_get_clock_mult_for_bus_mode(host); > + desired_rate = clock * mult; > + rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), desired_rate); > if (rc) { > pr_err("%s: Failed to set clock at rate %u at timing %d\n", > - mmc_hostname(host->mmc), clock, > - curr_ios.timing); > + mmc_hostname(host->mmc), desired_rate, curr_ios.timing); > return; > } > > @@ -371,11 +372,14 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, > * encounter it. > */ > achieved_rate = clk_get_rate(core_clk); > - if (achieved_rate > clock) > + if (achieved_rate > desired_rate) > pr_warn("%s: Card appears overclocked; req %u Hz, actual %lu Hz\n", > - mmc_hostname(host->mmc), clock, achieved_rate); > + mmc_hostname(host->mmc), desired_rate, achieved_rate); > + host->mmc->actual_clock = achieved_rate / mult; > + > + /* Stash the rate we requested to use in sdhci_msm_runtime_resume() */ > + msm_host->clk_rate = desired_rate; > > - msm_host->clk_rate = clock; > pr_debug("%s: Setting clock at rate %lu at timing %d\n", > mmc_hostname(host->mmc), achieved_rate, curr_ios.timing); > } > @@ -1756,13 +1760,6 @@ static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host) > static void __sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) > { > u16 clk; > - /* > - * Keep actual_clock as zero - > - * - since there is no divider used so no need of having actual_clock. > - * - MSM controller uses SDCLK for data timeout calculation. If > - * actual_clock is zero, host->clock is taken for calculation. > - */ > - host->mmc->actual_clock = 0; > > sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL); > > @@ -1785,7 +1782,7 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) > struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host); > > if (!clock) { > - msm_host->clk_rate = clock; > + host->mmc->actual_clock = msm_host->clk_rate = 0; > goto out; > } > > -- > 2.29.2.576.ga3fc446d84-goog >
diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c index 50beb407dbe9..f5669dc858d0 100644 --- a/drivers/mmc/host/sdhci-msm.c +++ b/drivers/mmc/host/sdhci-msm.c @@ -328,8 +328,7 @@ static void sdhci_msm_v5_variant_writel_relaxed(u32 val, writel_relaxed(val, host->ioaddr + offset); } -static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, - unsigned int clock) +static unsigned int msm_get_clock_mult_for_bus_mode(struct sdhci_host *host) { struct mmc_ios ios = host->mmc->ios; /* @@ -342,8 +341,8 @@ static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host, ios.timing == MMC_TIMING_MMC_DDR52 || ios.timing == MMC_TIMING_MMC_HS400 || host->flags & SDHCI_HS400_TUNING) - clock *= 2; - return clock; + return 2; + return 1; } static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, @@ -354,14 +353,16 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, struct mmc_ios curr_ios = host->mmc->ios; struct clk *core_clk = msm_host->bulk_clks[0].clk; unsigned long achieved_rate; + unsigned int desired_rate; + unsigned int mult; int rc; - clock = msm_get_clock_rate_for_bus_mode(host, clock); - rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), clock); + mult = msm_get_clock_mult_for_bus_mode(host); + desired_rate = clock * mult; + rc = dev_pm_opp_set_rate(mmc_dev(host->mmc), desired_rate); if (rc) { pr_err("%s: Failed to set clock at rate %u at timing %d\n", - mmc_hostname(host->mmc), clock, - curr_ios.timing); + mmc_hostname(host->mmc), desired_rate, curr_ios.timing); return; } @@ -371,11 +372,14 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, * encounter it. */ achieved_rate = clk_get_rate(core_clk); - if (achieved_rate > clock) + if (achieved_rate > desired_rate) pr_warn("%s: Card appears overclocked; req %u Hz, actual %lu Hz\n", - mmc_hostname(host->mmc), clock, achieved_rate); + mmc_hostname(host->mmc), desired_rate, achieved_rate); + host->mmc->actual_clock = achieved_rate / mult; + + /* Stash the rate we requested to use in sdhci_msm_runtime_resume() */ + msm_host->clk_rate = desired_rate; - msm_host->clk_rate = clock; pr_debug("%s: Setting clock at rate %lu at timing %d\n", mmc_hostname(host->mmc), achieved_rate, curr_ios.timing); } @@ -1756,13 +1760,6 @@ static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host) static void __sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) { u16 clk; - /* - * Keep actual_clock as zero - - * - since there is no divider used so no need of having actual_clock. - * - MSM controller uses SDCLK for data timeout calculation. If - * actual_clock is zero, host->clock is taken for calculation. - */ - host->mmc->actual_clock = 0; sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL); @@ -1785,7 +1782,7 @@ static void sdhci_msm_set_clock(struct sdhci_host *host, unsigned int clock) struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host); if (!clock) { - msm_host->clk_rate = clock; + host->mmc->actual_clock = msm_host->clk_rate = 0; goto out; }