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]. [1] http://lore.kernel.org/r/20201210102234.1.I096779f219625148900fc984dd0084ed1ba87c7f@changeid Suggested-by: Stephen Boyd <swb...@chromium.org> Signed-off-by: Douglas Anderson <diand...@chromium.org> --- drivers/mmc/host/sdhci-msm.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c index 3451eb325513..dd41f6a4dbfb 100644 --- a/drivers/mmc/host/sdhci-msm.c +++ b/drivers/mmc/host/sdhci-msm.c @@ -353,6 +353,7 @@ 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 int achieved_rate; int rc; clock = msm_get_clock_rate_for_bus_mode(host, clock); @@ -363,6 +364,17 @@ 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 %d 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), -- 2.29.2.576.ga3fc446d84-goog