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[82.243.161.21]) by smtp.googlemail.com with ESMTPSA id c20sm98716866wre.28.2019.04.17.13.44.11 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 Apr 2019 13:44:11 -0700 (PDT) From: Jerome Brunet To: Ulf Hansson , Kevin Hilman Cc: Jerome Brunet , linux-mmc@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 5/7] mmc: meson-gx: avoid clock glitch when switching to DDR modes Date: Wed, 17 Apr 2019 22:43:53 +0200 Message-Id: <20190417204355.469-6-jbrunet@baylibre.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190417204355.469-1-jbrunet@baylibre.com> References: <20190417204355.469-1-jbrunet@baylibre.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Activating DDR in the Amlogic mmc controller, among other things, will divide the output clock by 2. So by activating it with clock on, we are creating a glitch on the output. Instead, let's deal with DDR when the clock output is off, when setting the clock. Signed-off-by: Jerome Brunet --- drivers/mmc/host/meson-gx-mmc.c | 72 +++++++++++++++++++-------------- 1 file changed, 42 insertions(+), 30 deletions(-) -- 2.20.1 diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c index 118f09da8dfb..f77b9327a590 100644 --- a/drivers/mmc/host/meson-gx-mmc.c +++ b/drivers/mmc/host/meson-gx-mmc.c @@ -169,6 +169,7 @@ struct meson_host { struct clk *rx_clk; struct clk *tx_clk; unsigned long req_rate; + bool ddr; struct pinctrl *pinctrl; struct pinctrl_state *pins_default; @@ -384,16 +385,6 @@ static void meson_mmc_post_req(struct mmc_host *mmc, struct mmc_request *mrq, mmc_get_dma_dir(data)); } -static bool meson_mmc_timing_is_ddr(struct mmc_ios *ios) -{ - if (ios->timing == MMC_TIMING_MMC_DDR52 || - ios->timing == MMC_TIMING_UHS_DDR50 || - ios->timing == MMC_TIMING_MMC_HS400) - return true; - - return false; -} - /* * Gating the clock on this controller is tricky. It seems the mmc clock * is also used by the controller. It may crash during some operation if the @@ -430,36 +421,41 @@ static void meson_mmc_clk_ungate(struct meson_host *host) writel(cfg, host->regs + SD_EMMC_CFG); } -static int meson_mmc_clk_set(struct meson_host *host, struct mmc_ios *ios) +static int meson_mmc_clk_set(struct meson_host *host, unsigned long rate, + bool ddr) { struct mmc_host *mmc = host->mmc; - unsigned long rate = ios->clock; int ret; u32 cfg; - /* DDR modes require higher module clock */ - if (meson_mmc_timing_is_ddr(ios)) - rate <<= 1; - /* Same request - bail-out */ - if (host->req_rate == rate) + if (host->ddr == ddr && host->req_rate == rate) return 0; /* stop clock */ meson_mmc_clk_gate(host); host->req_rate = 0; + mmc->actual_clock = 0; - if (!rate) { - mmc->actual_clock = 0; - /* return with clock being stopped */ + /* return with clock being stopped */ + if (!rate) return 0; - } /* Stop the clock during rate change to avoid glitches */ cfg = readl(host->regs + SD_EMMC_CFG); cfg |= CFG_STOP_CLOCK; writel(cfg, host->regs + SD_EMMC_CFG); + if (ddr) { + /* DDR modes require higher module clock */ + rate <<= 1; + cfg |= CFG_DDR; + } else { + cfg &= ~CFG_DDR; + } + writel(cfg, host->regs + SD_EMMC_CFG); + host->ddr = ddr; + ret = clk_set_rate(host->mmc_clk, rate); if (ret) { dev_err(host->dev, "Unable to set cfg_div_clk to %lu. ret=%d\n", @@ -471,12 +467,14 @@ static int meson_mmc_clk_set(struct meson_host *host, struct mmc_ios *ios) mmc->actual_clock = clk_get_rate(host->mmc_clk); /* We should report the real output frequency of the controller */ - if (meson_mmc_timing_is_ddr(ios)) + if (ddr) { + host->req_rate >>= 1; mmc->actual_clock >>= 1; + } dev_dbg(host->dev, "clk rate: %u Hz\n", mmc->actual_clock); - if (ios->clock != mmc->actual_clock) - dev_dbg(host->dev, "requested rate was %u\n", ios->clock); + if (rate != mmc->actual_clock) + dev_dbg(host->dev, "requested rate was %lu\n", rate); /* (re)start clock */ meson_mmc_clk_ungate(host); @@ -750,6 +748,25 @@ static int meson_mmc_execute_tuning(struct mmc_host *mmc, u32 opcode) return meson_mmc_clk_phase_tuning(mmc, opcode, host->rx_clk); } +static int meson_mmc_prepare_ios_clock(struct meson_host *host, + struct mmc_ios *ios) +{ + bool ddr; + + switch (ios->timing) { + case MMC_TIMING_MMC_DDR52: + case MMC_TIMING_UHS_DDR50: + ddr = true; + break; + + default: + ddr = false; + break; + } + + return meson_mmc_clk_set(host, ios->clock, ddr); +} + static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) { struct meson_host *host = mmc_priv(mmc); @@ -819,15 +836,10 @@ static void meson_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) val &= ~CFG_BUS_WIDTH_MASK; val |= FIELD_PREP(CFG_BUS_WIDTH_MASK, bus_width); - val &= ~CFG_DDR; - if (meson_mmc_timing_is_ddr(ios)) - val |= CFG_DDR; - - err = meson_mmc_clk_set(host, ios); + err = meson_mmc_prepare_ios_clock(host, ios); if (err) dev_err(host->dev, "Failed to set clock: %d\n,", err); - writel(val, host->regs + SD_EMMC_CFG); dev_dbg(host->dev, "SD_EMMC_CFG: 0x%08x\n", val); }