[PATCH V1 10/11] mmc: tegra: fix CQE resume sequence

Sowjanya Komatineni
2019-03-02T05:21:04Z

Tegra CQHCI/SDHCI design prevents write access to SDHCI block size
register when CQE is enabled and unhalted.

CQHCI driver enabled CQE prior to invoking sdhci_cqe_enable which
violates this Tegra specific host requirement.

This patch fixes this by configuring sdhci block registers prior
to CQE unhalt.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
---
drivers/mmc/host/sdhci-tegra.c | 71 ++++++++++++++++++++++++++++++++++++------
1 file changed, 62 insertions(+), 9 deletions(-)

diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
index 2b63626dc2fa..7063cfcdc590 100644
--- a/drivers/mmc/host/sdhci-tegra.c
+++ b/drivers/mmc/host/sdhci-tegra.c
@@ -1126,23 +1126,75 @@ static void tegra_sdhci_voltage_switch(struct sdhci_host *host)
tegra_host->pad_calib_required = true;
}

+static void tegra_cqhci_writel(struct cqhci_host *cq_host, u32 val, int reg)
+{
+ struct mmc_host *mmc = cq_host->mmc;
+ u8 ctrl;
+ ktime_t timeout;
+ bool timed_out;
+
+ /*
+ * During CQE resume/unhalt, CQHCI driver unhalts CQE prior to
+ * cqhci_host_ops enable where SDHCI DMA and BLOCK_SIZE registers need
+ * to be re-configured.
+ * Tegra CQHCI/SDHCI prevents write access to block size register when
+ * CQE is unhalted. So handling CQE resume sequence here to configure
+ * SDHCI block registers prior to exiting CQE halt state.
+ */
+ if (reg == CQHCI_CTL && !(val & CQHCI_HALT) &&
+ cqhci_readl(cq_host, CQHCI_CTL) & CQHCI_HALT) {
+ sdhci_cqe_enable(mmc);
+ writel(val, cq_host->mmio + reg);
+ timeout = ktime_add_us(ktime_get(), 50);
+ while (1) {
+ timed_out = ktime_compare(ktime_get(), timeout) > 0;
+ ctrl = cqhci_readl(cq_host, CQHCI_CTL);
+ if (!(ctrl & CQHCI_HALT) || timed_out)
+ break;
+ }
+ /*
+ * CQE usually resumes very quick, but incase if Tegra CQE
+ * doesn't resume retry unhalt.
+ */
+ if (timed_out)
+ writel(val, cq_host->mmio + reg);
+ } else {
+ writel(val, cq_host->mmio + reg);
+ }
+}
+
static void sdhci_tegra_cqe_enable(struct mmc_host *mmc)
{
struct cqhci_host *cq_host = mmc->cqe_private;
- u32 cqcfg = 0;
+ u32 val;

/*
- * Tegra SDMMC Controller design prevents write access to BLOCK_COUNT
- * registers when CQE is enabled.
+ * Tegra CQHCI/SDMMC design prevents write access to sdhci block size
+ * register when CQE is enabled and unhalted.
+ * CQHCI driver enables CQE prior to activation, so disable CQE before
+ * programming block size in sdhci controller and enable it back.
*/
- cqcfg = cqhci_readl(cq_host, CQHCI_CFG);
- if (cqcfg & CQHCI_ENABLE)
- cqhci_writel(cq_host, (cqcfg & ~CQHCI_ENABLE), CQHCI_CFG);
+ if (!cq_host->activated) {
+ val = cqhci_readl(cq_host, CQHCI_CFG);
+ if (val & CQHCI_ENABLE)
+ cqhci_writel(cq_host, (val & ~CQHCI_ENABLE),
+ CQHCI_CFG);
+ sdhci_cqe_enable(mmc);
+ if (val & CQHCI_ENABLE)
+ cqhci_writel(cq_host, val, CQHCI_CFG);
+ }

- sdhci_cqe_enable(mmc);
+ /*
+ * CMD CRC errors are seen sometimes with some eMMC devices when status
+ * command is sent during transfer of last data block which is the
+ * default case as send status command block counter (CBC) is 1.
+ * So changing send status command block counter (CBC) to 0 to allow
+ * send status command only when the data lines are idle.
+ */
+ val = cqhci_readl(cq_host, CQHCI_SSC1);
+ val &= ~CQHCI_SSC1_CBC_MASK;
+ cqhci_writel(cq_host, val, CQHCI_SSC1);

- if (cqcfg & CQHCI_ENABLE)
- cqhci_writel(cq_host, cqcfg, CQHCI_CFG);
}

static void sdhci_tegra_dumpregs(struct mmc_host *mmc)
@@ -1167,6 +1219,7 @@ static const struct cqhci_host_ops sdhci_tegra_cqhci_ops = {
.enable = sdhci_tegra_cqe_enable,
.disable = sdhci_cqe_disable,
.dumpregs = sdhci_tegra_dumpregs,
+ .write_l = tegra_cqhci_writel,
};

static const struct sdhci_ops tegra_sdhci_ops = {
--
2.7.4