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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id h2sm1394492otn.15.2020.12.10.14.23.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Dec 2020 14:23:33 -0800 (PST) Date: Thu, 10 Dec 2020 16:23:31 -0600 From: Bjorn Andersson To: Douglas Anderson Cc: Ulf Hansson , Adrian Hunter , Stephen Boyd , vbadigan@codeaurora.org, Taniya Das , Andy Gross , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org Subject: Re: [PATCH v3] mmc: sdhci-msm: Warn about overclocking SD/MMC Message-ID: References: <20201210132745.v3.1.Iec3430c7d3c2a29262695edef7b82a14aaa567e5@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201210132745.v3.1.Iec3430c7d3c2a29262695edef7b82a14aaa567e5@changeid> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 10 Dec 15:27 CST 2020, Douglas Anderson wrote: > 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 > Signed-off-by: Douglas Anderson Reviewed-by: Bjorn Andersson Regards, Bjorn > --- > > Changes in v3: > - Proper printf format code. > > Changes in v2: > - Store rate in unsigned long, not unsigned int. > - Reuse the clk_get_rate() in the later print. > > drivers/mmc/host/sdhci-msm.c | 15 +++++++++++++-- > 1 file changed, 13 insertions(+), 2 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c > index 3451eb325513..50beb407dbe9 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 long achieved_rate; > int rc; > > clock = msm_get_clock_rate_for_bus_mode(host, clock); > @@ -363,10 +364,20 @@ 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 */ > -- > 2.29.2.576.ga3fc446d84-goog >