Re: [PATCH] mmc: mediatek: fix SDIO irq issue

[Ulf Hansson <ulf.hansson@linaro.org>]

On Tue, 21 Jan 2020 at 08:21, Yong Mao <yong.mao@mediatek.com> wrote:
>
> From: yong mao <yong.mao@mediatek.com>
>
> Host controller may lost interrupt in some specail case.

Please explain a bit more about the special cases. When and how often
does it happen?

> Add SDIO irq recheck mechanism to make sure all interrupts
> can be processed immediately.
>
> Signed-off-by: Yong Mao <yong.mao@mediatek.com>
> ---
>  drivers/mmc/host/mtk-sd.c | 38 ++++++++++++++++++++++++++++++++++++++
>  1 file changed, 38 insertions(+)
>
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 7726dcf..18a1b86 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -128,6 +128,7 @@
>  #define MSDC_PS_CDSTS           (0x1 << 1)     /* R  */
>  #define MSDC_PS_CDDEBOUNCE      (0xf << 12)    /* RW */
>  #define MSDC_PS_DAT             (0xff << 16)   /* R  */
> +#define MSDC_PS_DATA1           (0x1 << 17)    /* R  */
>  #define MSDC_PS_CMD             (0x1 << 24)    /* R  */
>  #define MSDC_PS_WP              (0x1 << 31)    /* R  */
>
> @@ -361,6 +362,7 @@ struct msdc_save_para {
>
>  struct mtk_mmc_compatible {
>         u8 clk_div_bits;
> +       bool recheck_sdio_irq;
>         bool hs400_tune; /* only used for MT8173 */
>         u32 pad_tune_reg;
>         bool async_fifo;
> @@ -436,6 +438,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt8135_compat = {
>         .clk_div_bits = 8,
> +       .recheck_sdio_irq = false,
>         .hs400_tune = false,
>         .pad_tune_reg = MSDC_PAD_TUNE,
>         .async_fifo = false,
> @@ -448,6 +451,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt8173_compat = {
>         .clk_div_bits = 8,
> +       .recheck_sdio_irq = true,
>         .hs400_tune = true,
>         .pad_tune_reg = MSDC_PAD_TUNE,
>         .async_fifo = false,
> @@ -460,6 +464,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt8183_compat = {
>         .clk_div_bits = 12,
> +       .recheck_sdio_irq = false,
>         .hs400_tune = false,
>         .pad_tune_reg = MSDC_PAD_TUNE0,
>         .async_fifo = true,
> @@ -472,6 +477,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt2701_compat = {
>         .clk_div_bits = 12,
> +       .recheck_sdio_irq = false,
>         .hs400_tune = false,
>         .pad_tune_reg = MSDC_PAD_TUNE0,
>         .async_fifo = true,
> @@ -484,6 +490,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt2712_compat = {
>         .clk_div_bits = 12,
> +       .recheck_sdio_irq = false,
>         .hs400_tune = false,
>         .pad_tune_reg = MSDC_PAD_TUNE0,
>         .async_fifo = true,
> @@ -496,6 +503,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt7622_compat = {
>         .clk_div_bits = 12,
> +       .recheck_sdio_irq = false,
>         .hs400_tune = false,
>         .pad_tune_reg = MSDC_PAD_TUNE0,
>         .async_fifo = true,
> @@ -508,6 +516,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt8516_compat = {
>         .clk_div_bits = 12,
> +       .recheck_sdio_irq = false,
>         .hs400_tune = false,
>         .pad_tune_reg = MSDC_PAD_TUNE0,
>         .async_fifo = true,
> @@ -518,6 +527,7 @@ struct msdc_host {
>
>  static const struct mtk_mmc_compatible mt7620_compat = {
>         .clk_div_bits = 8,
> +       .recheck_sdio_irq = false,
>         .hs400_tune = false,
>         .pad_tune_reg = MSDC_PAD_TUNE,
>         .async_fifo = false,
> @@ -1007,6 +1017,30 @@ static int msdc_auto_cmd_done(struct msdc_host *host, int events,
>         return cmd->error;
>  }
>
> +/**
> + * msdc_recheck_sdio_irq - recheck whether the SDIO irq is lost
> + *
> + * Host controller may lost interrupt in some special case.
> + * Add SDIO irq recheck mechanism to make sure all interrupts
> + * can be processed immediately
> + *
> + */
> +static void msdc_recheck_sdio_irq(struct msdc_host *host)
> +{
> +       u32 reg_int, reg_inten, reg_ps;
> +
> +       if ((host->mmc->caps & MMC_CAP_SDIO_IRQ)) {
> +               reg_inten = readl(host->base + MSDC_INTEN);
> +               if (reg_inten & MSDC_INTEN_SDIOIRQ) {
> +                       reg_int = readl(host->base + MSDC_INT);
> +                       reg_ps = readl(host->base + MSDC_PS);
> +                       if (!((reg_int & MSDC_INT_SDIOIRQ) ||
> +                             (reg_ps & MSDC_PS_DATA1)))

This looks a bit unnecessary complicated and there are more
parentheses than needed.

I am also wondering about the logic. This looks like you want to
signal an SDIO IRQ when both MSDC_INT_SDIOIRQ and MSDC_PS_DATA1 are
cleared. Is that really correct?

Moreover, this means that you will be polling the registers for each
every request you complete. This sounds quite inefficient and I wonder
if it can be done more seldom, perhaps via a timer event instead. And,
what if there is no request for a while, then this means the re-check
doesn't gets to run. Could that be a problem?

> +                               sdio_signal_irq(host->mmc);

Before calling sdio_signal_irq(), the SDIO IRQ needs to be temporarily
disabled. In other words, looks like you should be calling
__msdc_enable_sdio_irq(0) from here as well.

> +               }
> +       }
> +}
> +
>  static void msdc_track_cmd_data(struct msdc_host *host,
>                                 struct mmc_command *cmd, struct mmc_data *data)
>  {
> @@ -1035,6 +1069,8 @@ static void msdc_request_done(struct msdc_host *host, struct mmc_request *mrq)
>         if (host->error)
>                 msdc_reset_hw(host);
>         mmc_request_done(host->mmc, mrq);
> +       if (host->dev_comp->recheck_sdio_irq)
> +               msdc_recheck_sdio_irq(host);
>  }
>
>  /* returns true if command is fully handled; returns false otherwise */
> @@ -1393,6 +1429,8 @@ static void __msdc_enable_sdio_irq(struct msdc_host *host, int enb)
>         if (enb) {
>                 sdr_set_bits(host->base + MSDC_INTEN, MSDC_INTEN_SDIOIRQ);
>                 sdr_set_bits(host->base + SDC_CFG, SDC_CFG_SDIOIDE);
> +               if (host->dev_comp->recheck_sdio_irq)
> +                       msdc_recheck_sdio_irq(host);
>         } else {
>                 sdr_clr_bits(host->base + MSDC_INTEN, MSDC_INTEN_SDIOIRQ);
>                 sdr_clr_bits(host->base + SDC_CFG, SDC_CFG_SDIOIDE);
> --
> 1.9.1

Kind regards
Uffe