Re: [PATCH v3] mmc: sdhci-tegra: Fix switch to HS400ES mode
From: Adrian Hunter <adrian.hunter@intel.com>
Date: 2021-12-14 06:01:32
Also in:
linux-mmc, lkml
On 06/12/2021 16:05, Prathamesh Shete wrote:
When CMD13 is sent after switching to HS400ES mode, the bus is operating at either MMC_HIGH_26_MAX_DTR or MMC_HIGH_52_MAX_DTR. To meet Tegra SDHCI requirement at HS400ES mode, force SDHCI interface clock to MMC_HS200_MAX_DTR (200 MHz) so that host controller CAR clock and the interface clock are rate matched. Signed-off-by: Prathamesh Shete <redacted>
One minor comment below otherwise: Acked-by: Adrian Hunter <adrian.hunter@intel.com>
quoted hunk ↗ jump to hunk
--- drivers/mmc/host/sdhci-tegra.c | 43 ++++++++++++++++++++-------------- 1 file changed, 26 insertions(+), 17 deletions(-)diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c index 387ce9cdbd7c..ddaa3d9000f6 100644 --- a/drivers/mmc/host/sdhci-tegra.c +++ b/drivers/mmc/host/sdhci-tegra.c@@ -354,23 +354,6 @@ static void tegra_sdhci_set_tap(struct sdhci_host *host, unsigned int tap) } } -static void tegra_sdhci_hs400_enhanced_strobe(struct mmc_host *mmc, - struct mmc_ios *ios) -{ - struct sdhci_host *host = mmc_priv(mmc); - u32 val; - - val = sdhci_readl(host, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL); - - if (ios->enhanced_strobe) - val |= SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE; - else - val &= ~SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE; - - sdhci_writel(host, val, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL); - -} - static void tegra_sdhci_reset(struct sdhci_host *host, u8 mask) { struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);@@ -791,6 +774,32 @@ static void tegra_sdhci_set_clock(struct sdhci_host *host, unsigned int clock) } } +static void tegra_sdhci_hs400_enhanced_strobe(struct mmc_host *mmc, + struct mmc_ios *ios) +{ + struct sdhci_host *host = mmc_priv(mmc); + u32 val; + + val = sdhci_readl(host, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL); + + if (ios->enhanced_strobe) { + val |= SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE; + /* + * When CMD13 is sent from mmc_select_hs400es() after + * switching to HS400ES mode, the bus is operating at + * either MMC_HIGH_26_MAX_DTR or MMC_HIGH_52_MAX_DTR. + * To meet Tegra SDHCI requirement at HS400ES mode, force SDHCI + * interface clock to MMC_HS200_MAX_DTR (200 MHz) so that host + * controller CAR clock and the interface clock are rate matched. + */ + tegra_sdhci_set_clock(host, MMC_HS200_MAX_DTR);
Comment and line above need indenting
+ } else {
+ val &= ~SDHCI_TEGRA_SYS_SW_CTRL_ENHANCED_STROBE;
+ }
+
+ sdhci_writel(host, val, SDHCI_TEGRA_VENDOR_SYS_SW_CTRL);
+}
+
static unsigned int tegra_sdhci_get_max_clock(struct sdhci_host *host)
{
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);