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Message-ID: <CAPDyKFrBUcqwuwVJsVi1JrG+0S=vWJ7D-BjQhjg-AU0GsbKO1Q@mail.gmail.com>
Date:   Tue, 26 Sep 2023 12:29:45 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Yann Gautier <yann.gautier@...s.st.com>
Cc:     Russell King <linux@...linux.org.uk>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Christophe Kerello <christophe.kerello@...s.st.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Rob Herring <robh@...nel.org>, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] mmc: mmci: stm32: add SDIO in-band interrupt mode

On Thu, 14 Sept 2023 at 17:09, Yann Gautier <yann.gautier@...s.st.com> wrote:
>
> From: Christophe Kerello <christophe.kerello@...s.st.com>
>
> Add the support of SDIO in-band interrupt mode for STM32 and Ux500
> variants.
> It allows the SD I/O card to interrupt the host on SDMMC_D1 data line.
> It is not enabled by default on Ux500 variant as this is unstable and
> Ux500 users should use out-of-band IRQs.
>
> Signed-off-by: Christophe Kerello <christophe.kerello@...s.st.com>
> Signed-off-by: Yann Gautier <yann.gautier@...s.st.com>
> ---
> Updates on v2:
> * rename use_sdio_irq to supports_sdio_irq and change it to bool
> * use common code for ux500 and stm32 variants
>
> ---
>  drivers/mmc/host/mmci.c             | 85 +++++++++++++++++++++++++++++
>  drivers/mmc/host/mmci.h             |  7 +++
>  drivers/mmc/host/mmci_stm32_sdmmc.c |  2 +
>  3 files changed, 94 insertions(+)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index dda756a563793..65cc03ee7f23b 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -272,6 +272,7 @@ static struct variant_data variant_stm32_sdmmc = {
>         .datactrl_mask_sdio     = MCI_DPSM_ST_SDIOEN,
>         .stm32_idmabsize_mask   = GENMASK(12, 5),
>         .stm32_idmabsize_align  = BIT(5),
> +       .supports_sdio_irq      = true,
>         .busy_timeout           = true,
>         .busy_detect            = true,
>         .busy_detect_flag       = MCI_STM32_BUSYD0,
> @@ -299,6 +300,7 @@ static struct variant_data variant_stm32_sdmmcv2 = {
>         .datactrl_mask_sdio     = MCI_DPSM_ST_SDIOEN,
>         .stm32_idmabsize_mask   = GENMASK(16, 5),
>         .stm32_idmabsize_align  = BIT(5),
> +       .supports_sdio_irq      = true,
>         .dma_lli                = true,
>         .busy_timeout           = true,
>         .busy_detect            = true,
> @@ -327,6 +329,7 @@ static struct variant_data variant_stm32_sdmmcv3 = {
>         .datactrl_mask_sdio     = MCI_DPSM_ST_SDIOEN,
>         .stm32_idmabsize_mask   = GENMASK(16, 6),
>         .stm32_idmabsize_align  = BIT(6),
> +       .supports_sdio_irq      = true,
>         .dma_lli                = true,
>         .busy_timeout           = true,
>         .busy_detect            = true,
> @@ -423,6 +426,11 @@ static void mmci_write_datactrlreg(struct mmci_host *host, u32 datactrl)
>         /* Keep busy mode in DPSM if enabled */
>         datactrl |= host->datactrl_reg & host->variant->busy_dpsm_flag;
>
> +       /* Keep SD I/O interrupt mode enabled */
> +       if (host->variant->supports_sdio_irq &&
> +           host->mmc->caps & MMC_CAP_SDIO_IRQ)
> +               datactrl |= host->variant->datactrl_mask_sdio;
> +

This doesn't look entirely correct to me, as it will make the
->datactrl_mask_sdio bit to be set even when it shouldn't. If I
understand correctly, we really want the bit to be set if the SDIO
irqs has been enabled, but otherwise leave it for mmci_start_data() to
manage it, right?

That said, perhaps the comment a few lines above, deserves some
clarification too. Would rephrasing it into "Keep the SDIO mode bit if
SDIO irqs are enabled" make it more clear?

>From an implementation point of view, an idea is to add a
"host->datactrl_reg_add" variable (we have this for the clk and pwr
registers already). mmci_write_datactrlreg() should then OR these bits
when writing to the register. In this way, mmci_enable_sdio_irq() can
update the host->datactrl_reg_add with ->datactrl_mask_sdio, when
needed. This should also work for the ->busy_dpsm_flag a few lines
above, I think.

>         if (host->datactrl_reg != datactrl) {
>                 host->datactrl_reg = datactrl;
>                 writel(datactrl, host->base + MMCIDATACTRL);
> @@ -817,6 +825,25 @@ static bool ux500_busy_complete(struct mmci_host *host, struct mmc_command *cmd,
>         return (host->busy_state == MMCI_BUSY_DONE);
>  }
>
> +void ux500_and_stm32_enable_sdio_irq(struct mmci_host *host, int enable)
> +{
> +       void __iomem *base = host->base;
> +       u32 mask = readl_relaxed(base + MMCIMASK0);
> +
> +       if (enable)
> +               writel_relaxed(mask | MCI_ST_SDIOITMASK, base + MMCIMASK0);
> +       else
> +               writel_relaxed(mask & ~MCI_ST_SDIOITMASK, base + MMCIMASK0);
> +}
> +
> +void ux500_and_stm32_sdio_irq(struct mmci_host *host, u32 status)
> +{
> +       if (status & MCI_ST_SDIOIT) {
> +               ux500_and_stm32_enable_sdio_irq(host, 0);
> +               sdio_signal_irq(host->mmc);
> +       }
> +}
> +
>  /*
>   * All the DMA operation mode stuff goes inside this ifdef.
>   * This assumes that you have a generic DMA device interface,
> @@ -1191,6 +1218,8 @@ static void ux500_variant_init(struct mmci_host *host)
>  {
>         host->ops = &mmci_variant_ops;
>         host->ops->busy_complete = ux500_busy_complete;
> +       host->ops->enable_sdio_irq = ux500_and_stm32_enable_sdio_irq;
> +       host->ops->sdio_irq = ux500_and_stm32_sdio_irq;
>  }
>
>  static void ux500v2_variant_init(struct mmci_host *host)
> @@ -1198,6 +1227,8 @@ static void ux500v2_variant_init(struct mmci_host *host)
>         host->ops = &mmci_variant_ops;
>         host->ops->busy_complete = ux500_busy_complete;
>         host->ops->get_datactrl_cfg = ux500v2_get_dctrl_cfg;
> +       host->ops->enable_sdio_irq = ux500_and_stm32_enable_sdio_irq;
> +       host->ops->sdio_irq = ux500_and_stm32_sdio_irq;
>  }

It looks to me that the extra layer of mmci variant callbacks is a bit
"heavy" at this point. ux500 and the st variants seem to work very
similarly in this regard. So maybe just the mmci_ops callbacks
directly and stick to the mmci* prefix of the function names. At least
until we see a better reason to have the extra layer of callbacks.

Of course, this also means that we need to assign
mmci_ops->enable_sdio_irq|ack_sdio_irq() conditionally during probe,
based upon the variant->supports_sdio_irq bit.

>
>  static void mmci_pre_request(struct mmc_host *mmc, struct mmc_request *mrq)
> @@ -1805,6 +1836,11 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
>                         mmci_data_irq(host, host->data, status);
>                 }
>
> +               if (host->variant->supports_sdio_irq &&
> +                   host->mmc->caps & MMC_CAP_SDIO_IRQ &&

Checking the caps seems superfluous. The SDIO irqs must not be
enabled, unless MMC_CAP_SDIO_IRQ is supported, right?

> +                   host->ops && host->ops->sdio_irq)
> +                       host->ops->sdio_irq(host, status);
> +
>                 /*
>                  * Busy detection has been handled by mmci_cmd_irq() above.
>                  * Clear the status bit to prevent polling in IRQ context.
> @@ -2041,6 +2077,45 @@ static int mmci_sig_volt_switch(struct mmc_host *mmc, struct mmc_ios *ios)
>         return ret;
>  }
>
> +static void mmci_enable_sdio_irq(struct mmc_host *mmc, int enable)
> +{
> +       struct mmci_host *host = mmc_priv(mmc);
> +       unsigned long flags;
> +
> +       if (!host->variant->supports_sdio_irq)
> +               return;

According to the earlier comment above about the extra layers of
callbacks, this can then be checked during probe instead and dropped
from here.

> +
> +       if (host->ops && host->ops->enable_sdio_irq) {
> +               if (enable)
> +                       /* Keep device active while SDIO IRQ is enabled */
> +                       pm_runtime_get_sync(mmc_dev(mmc));
> +
> +               spin_lock_irqsave(&host->lock, flags);
> +               host->ops->enable_sdio_irq(host, enable);
> +               spin_unlock_irqrestore(&host->lock, flags);
> +
> +               if (!enable) {
> +                       pm_runtime_mark_last_busy(mmc_dev(mmc));
> +                       pm_runtime_put_autosuspend(mmc_dev(mmc));
> +               }
> +       }
> +}
> +
> +static void mmci_ack_sdio_irq(struct mmc_host *mmc)
> +{
> +       struct mmci_host *host = mmc_priv(mmc);
> +       unsigned long flags;
> +
> +       if (!host->variant->supports_sdio_irq)
> +               return;

Ditto.

> +
> +       if (host->ops && host->ops->enable_sdio_irq) {
> +               spin_lock_irqsave(&host->lock, flags);
> +               host->ops->enable_sdio_irq(host, 1);
> +               spin_unlock_irqrestore(&host->lock, flags);
> +       }
> +}
> +
>  static struct mmc_host_ops mmci_ops = {
>         .request        = mmci_request,
>         .pre_req        = mmci_pre_request,
> @@ -2049,6 +2124,8 @@ static struct mmc_host_ops mmci_ops = {
>         .get_ro         = mmc_gpio_get_ro,
>         .get_cd         = mmci_get_cd,
>         .start_signal_voltage_switch = mmci_sig_volt_switch,
> +       .enable_sdio_irq = mmci_enable_sdio_irq,
> +       .ack_sdio_irq   = mmci_ack_sdio_irq,
>  };
>
>  static void mmci_probe_level_translator(struct mmc_host *mmc)
> @@ -2316,6 +2393,14 @@ static int mmci_probe(struct amba_device *dev,
>                 mmc->caps |= MMC_CAP_WAIT_WHILE_BUSY;
>         }
>
> +       if (variant->supports_sdio_irq && host->mmc->caps & MMC_CAP_SDIO_IRQ) {
> +               mmc->caps2 |= MMC_CAP2_SDIO_IRQ_NOTHREAD;
> +
> +               if (variant->datactrl_mask_sdio)
> +                       mmci_write_datactrlreg(host,
> +                                              host->variant->datactrl_mask_sdio);

As I stated earlier, it looks to me that this should be managed when
enabling/disabling the SDIO irqs and not during probe. No?

> +       }
> +
>         /* Variants with mandatory busy timeout in HW needs R1B responses. */
>         if (variant->busy_timeout)
>                 mmc->caps |= MMC_CAP_NEED_RSP_BUSY;
> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> index 253197f132fca..5ea4975c18ec5 100644
> --- a/drivers/mmc/host/mmci.h
> +++ b/drivers/mmc/host/mmci.h
> @@ -331,6 +331,7 @@ enum mmci_busy_state {
>   *            register.
>   * @opendrain: bitmask identifying the OPENDRAIN bit inside MMCIPOWER register
>   * @dma_lli: true if variant has dma link list feature.
> + * @supports_sdio_irq: allow SD I/O card to interrupt the host
>   * @stm32_idmabsize_mask: stm32 sdmmc idma buffer size.
>   */
>  struct variant_data {
> @@ -376,6 +377,7 @@ struct variant_data {
>         u32                     start_err;
>         u32                     opendrain;
>         u8                      dma_lli:1;
> +       bool                    supports_sdio_irq;
>         u32                     stm32_idmabsize_mask;
>         u32                     stm32_idmabsize_align;
>         void (*init)(struct mmci_host *host);
> @@ -400,6 +402,8 @@ struct mmci_host_ops {
>         bool (*busy_complete)(struct mmci_host *host, struct mmc_command *cmd, u32 status, u32 err_msk);
>         void (*pre_sig_volt_switch)(struct mmci_host *host);
>         int (*post_sig_volt_switch)(struct mmci_host *host, struct mmc_ios *ios);
> +       void (*enable_sdio_irq)(struct mmci_host *host, int enable);
> +       void (*sdio_irq)(struct mmci_host *host, u32 status);
>  };
>
>  struct mmci_host {
> @@ -481,6 +485,9 @@ void mmci_dmae_finalize(struct mmci_host *host, struct mmc_data *data);
>  void mmci_dmae_error(struct mmci_host *host);
>  #endif
>
> +void ux500_and_stm32_enable_sdio_irq(struct mmci_host *host, int enable);
> +void ux500_and_stm32_sdio_irq(struct mmci_host *host, u32 status);
> +
>  #ifdef CONFIG_MMC_QCOM_DML
>  void qcom_variant_init(struct mmci_host *host);
>  #else
> diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
> index 35067e1e6cd80..fbfaa0bcec51e 100644
> --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
> +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
> @@ -681,6 +681,8 @@ static struct mmci_host_ops sdmmc_variant_ops = {
>         .busy_complete = sdmmc_busy_complete,
>         .pre_sig_volt_switch = sdmmc_pre_sig_volt_vswitch,
>         .post_sig_volt_switch = sdmmc_post_sig_volt_switch,
> +       .enable_sdio_irq = ux500_and_stm32_enable_sdio_irq,
> +       .sdio_irq = ux500_and_stm32_sdio_irq,
>  };
>
>  static struct sdmmc_tuning_ops dlyb_tuning_mp15_ops = {
> --
> 2.34.1
>

Kind regards
Uffe

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