[PATCH 5.15 093/128] mmc: sdhci-tegra: Fix switch to HS400ES mode

Greg Kroah-Hartman
2021-12-27T15:52:14Z

From: Prathamesh Shete <pshete@nvidia.com>

commit 4fc7261dbab139d3c64c3b618262504e16cfe7ee upstream.

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 <pshete@nvidia.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Fixes: dfc9700cef77 ("mmc: tegra: Implement HS400 enhanced strobe")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211214113653.4631-1-pshete@nvidia.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/mmc/host/sdhci-tegra.c | 43 ++++++++++++++++++++++++-----------------
1 file changed, 26 insertions(+), 17 deletions(-)

--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -356,23 +356,6 @@ static void tegra_sdhci_set_tap(struct s
}
}

-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);
@@ -793,6 +776,32 @@ static void tegra_sdhci_set_clock(struct
}
}

+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);
+ } 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);