diff options
| author | Douglas Anderson <dianders@chromium.org> | 2020-12-14 09:21:14 -0800 |
|---|---|---|
| committer | Ulf Hansson <ulf.hansson@linaro.org> | 2021-02-01 11:54:42 +0100 |
| commit | a8cd989e1a57dff3994cd113650afb0223c44ec6 (patch) | |
| tree | 585dbdfb0df534d71359f7e82adfcfbd160a667f /drivers/mmc/host | |
| parent | 3536b82e5853ec302c1803896c126725afb6d57c (diff) | |
| download | linux-a8cd989e1a57dff3994cd113650afb0223c44ec6.tar.gz | |
mmc: sdhci-msm: Warn about overclocking SD/MMC
As talked about in commit 5e4b7e82d497 ("clk: qcom: gcc-sdm845: Use
floor ops for sdcc clks"), most clocks handled by the Qualcomm clock
drivers are rounded _up_ by default instead of down. We should make
sure SD/MMC clocks are always rounded down in the clock drivers.
Let's add a warning in the Qualcomm SDHCI driver to help catch the
problem.
This would have saved a bunch of time [1].
NOTE: this doesn't actually fix any problems, it just makes it obvious
to devs that there is a problem and that should be an indication to
fix the clock driver.
[1] http://lore.kernel.org/r/20201210102234.1.I096779f219625148900fc984dd0084ed1ba87c7f@changeid
Suggested-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20201214092048.v5.1.Iec3430c7d3c2a29262695edef7b82a14aaa567e5@changeid
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc/host')
| -rw-r--r-- | drivers/mmc/host/sdhci-msm.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c index 9c7927b03253..4d8dd706007d 100644 --- a/drivers/mmc/host/sdhci-msm.c +++ b/drivers/mmc/host/sdhci-msm.c @@ -352,6 +352,7 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host); struct mmc_ios curr_ios = host->mmc->ios; struct clk *core_clk = msm_host->bulk_clks[0].clk; + unsigned long achieved_rate; int rc; clock = msm_get_clock_rate_for_bus_mode(host, clock); @@ -362,10 +363,20 @@ static void msm_set_clock_rate_for_bus_mode(struct sdhci_host *host, curr_ios.timing); return; } + + /* + * Qualcomm clock drivers by default round clock _up_ if they can't + * make the requested rate. This is not good for SD. Yell if we + * encounter it. + */ + achieved_rate = clk_get_rate(core_clk); + if (achieved_rate > clock) + pr_warn("%s: Card appears overclocked; req %u Hz, actual %lu Hz\n", + mmc_hostname(host->mmc), clock, achieved_rate); + msm_host->clk_rate = clock; pr_debug("%s: Setting clock at rate %lu at timing %d\n", - mmc_hostname(host->mmc), clk_get_rate(core_clk), - curr_ios.timing); + mmc_hostname(host->mmc), achieved_rate, curr_ios.timing); } /* Platform specific tuning */ |