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

Adrian Hunter
2019-03-08T13:01:26Z

On 2/03/19 7:20 AM, Sowjanya Komatineni wrote:
> 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>

Acked-by: Adrian Hunter <adrian.hunter@intel.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 = {
>