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[104.57.184.186]) by smtp.gmail.com with ESMTPSA id w21sm3963794ooj.32.2020.12.14.08.42.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 14 Dec 2020 08:42:51 -0800 (PST) Date: Mon, 14 Dec 2020 10:42:49 -0600 From: Bjorn Andersson To: Douglas Anderson Cc: Ulf Hansson , Adrian Hunter , Stephen Boyd , Taniya Das , vbadigan@codeaurora.org, Andy Gross , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org Subject: Re: [PATCH v4 2/2] mmc: sdhci-msm: Actually set the actual clock Message-ID: References: <20201211091150.v4.1.Iec3430c7d3c2a29262695edef7b82a14aaa567e5@changeid> <20201211091150.v4.2.I7564620993acd4baa63fa0e3925ca879a86d3ee3@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201211091150.v4.2.I7564620993acd4baa63fa0e3925ca879a86d3ee3@changeid> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 11 Dec 11:12 CST 2020, 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. > > Signed-off-by: Douglas Anderson Reviewed-by: Bjorn Andersson Regards, Bjorn > --- > > Changes in v4: > - ("mmc: sdhci-msm: Actually set the actual clock") new for v4. > > drivers/mmc/host/sdhci-msm.c | 32 ++++++++++++++------------------ > 1 file changed, 14 insertions(+), 18 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c > index 50beb407dbe9..08a3960001ad 100644 > --- a/drivers/mmc/host/sdhci-msm.c > +++ b/drivers/mmc/host/sdhci-msm.c > @@ -328,7 +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, > +static unsigned int msm_get_clock_mult_for_bus_mode(struct sdhci_host *host, > unsigned int clock) > { > struct mmc_ios ios = host->mmc->ios; > @@ -342,8 +342,8 @@ 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 +354,16 @@ 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, clock); > + 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 +373,12 @@ 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; > > - msm_host->clk_rate = clock; > + msm_host->clk_rate = desired_rate; > pr_debug("%s: Setting clock at rate %lu at timing %d\n", > mmc_hostname(host->mmc), achieved_rate, curr_ios.timing); > } > @@ -1756,13 +1759,6 @@ 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 +1781,7 @@ 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 >