Revert "mmc: moxart-mmc: Use sg_miter for PIO"

This reverts commit 3ee0e7c3e67cab83ffbbe7707b43df8d41c9fe47.

The patch is not working for unknown reasons and I would
need access to the hardware to fix the bug.

This shouldn't matter anyway: the Moxa Art is not expected
to use highmem, and sg_miter() is only necessary to have
to properly deal with highmem.

Reported-by: Sergei Antonov <saproj@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/mmc/host/moxart-mmc.c | 78 ++++++++++++++++++++++++-------------------
 1 file changed, 43 insertions(+), 35 deletions(-)


---
base-commit: 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0
change-id: 20240606-mmc-moxart-revert-beb833b07dcb

Best regards,

On Thu, 6 Jun 2024 at 20:17, Linus Walleij <linus.walleij@linaro.org> wrote:
>
> This reverts commit 3ee0e7c3e67cab83ffbbe7707b43df8d41c9fe47.
>
> The patch is not working for unknown reasons and I would
> need access to the hardware to fix the bug.
>
> This shouldn't matter anyway: the Moxa Art is not expected
> to use highmem, and sg_miter() is only necessary to have
> to properly deal with highmem.
>
> Reported-by: Sergei Antonov <saproj@gmail.com>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Applied for fixes, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/host/moxart-mmc.c | 78 ++++++++++++++++++++++++-------------------
>  1 file changed, 43 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
> index 9a5f75163aca..8ede4ce93271 100644
> --- a/drivers/mmc/host/moxart-mmc.c
> +++ b/drivers/mmc/host/moxart-mmc.c
> @@ -131,10 +131,12 @@ struct moxart_host {
>         struct dma_async_tx_descriptor  *tx_desc;
>         struct mmc_host                 *mmc;
>         struct mmc_request              *mrq;
> +       struct scatterlist              *cur_sg;
>         struct completion               dma_complete;
>         struct completion               pio_complete;
>
> -       struct sg_mapping_iter          sg_miter;
> +       u32                             num_sg;
> +       u32                             data_remain;
>         u32                             data_len;
>         u32                             fifo_width;
>         u32                             timeout;
> @@ -146,6 +148,35 @@ struct moxart_host {
>         bool                            is_removed;
>  };
>
> +static inline void moxart_init_sg(struct moxart_host *host,
> +                                 struct mmc_data *data)
> +{
> +       host->cur_sg = data->sg;
> +       host->num_sg = data->sg_len;
> +       host->data_remain = host->cur_sg->length;
> +
> +       if (host->data_remain > host->data_len)
> +               host->data_remain = host->data_len;
> +}
> +
> +static inline int moxart_next_sg(struct moxart_host *host)
> +{
> +       int remain;
> +       struct mmc_data *data = host->mrq->cmd->data;
> +
> +       host->cur_sg++;
> +       host->num_sg--;
> +
> +       if (host->num_sg > 0) {
> +               host->data_remain = host->cur_sg->length;
> +               remain = host->data_len - data->bytes_xfered;
> +               if (remain > 0 && remain < host->data_remain)
> +                       host->data_remain = remain;
> +       }
> +
> +       return host->num_sg;
> +}
> +
>  static int moxart_wait_for_status(struct moxart_host *host,
>                                   u32 mask, u32 *status)
>  {
> @@ -278,29 +309,14 @@ static void moxart_transfer_dma(struct mmc_data *data, struct moxart_host *host)
>
>  static void moxart_transfer_pio(struct moxart_host *host)
>  {
> -       struct sg_mapping_iter *sgm = &host->sg_miter;
>         struct mmc_data *data = host->mrq->cmd->data;
>         u32 *sgp, len = 0, remain, status;
>
>         if (host->data_len == data->bytes_xfered)
>                 return;
>
> -       /*
> -        * By updating sgm->consumes this will get a proper pointer into the
> -        * buffer at any time.
> -        */
> -       if (!sg_miter_next(sgm)) {
> -               /* This shold not happen */
> -               dev_err(mmc_dev(host->mmc), "ran out of scatterlist prematurely\n");
> -               data->error = -EINVAL;
> -               complete(&host->pio_complete);
> -               return;
> -       }
> -       sgp = sgm->addr;
> -       remain = sgm->length;
> -       if (remain > host->data_len)
> -               remain = host->data_len;
> -       sgm->consumed = 0;
> +       sgp = sg_virt(host->cur_sg);
> +       remain = host->data_remain;
>
>         if (data->flags & MMC_DATA_WRITE) {
>                 while (remain > 0) {
> @@ -315,7 +331,6 @@ static void moxart_transfer_pio(struct moxart_host *host)
>                                 sgp++;
>                                 len += 4;
>                         }
> -                       sgm->consumed += len;
>                         remain -= len;
>                 }
>
> @@ -332,22 +347,22 @@ static void moxart_transfer_pio(struct moxart_host *host)
>                                 sgp++;
>                                 len += 4;
>                         }
> -                       sgm->consumed += len;
>                         remain -= len;
>                 }
>         }
>
> -       data->bytes_xfered += sgm->consumed;
> -       if (host->data_len == data->bytes_xfered) {
> +       data->bytes_xfered += host->data_remain - remain;
> +       host->data_remain = remain;
> +
> +       if (host->data_len != data->bytes_xfered)
> +               moxart_next_sg(host);
> +       else
>                 complete(&host->pio_complete);
> -               return;
> -       }
>  }
>
>  static void moxart_prepare_data(struct moxart_host *host)
>  {
>         struct mmc_data *data = host->mrq->cmd->data;
> -       unsigned int flags = SG_MITER_ATOMIC; /* Used from IRQ */
>         u32 datactrl;
>         int blksz_bits;
>
> @@ -358,19 +373,15 @@ static void moxart_prepare_data(struct moxart_host *host)
>         blksz_bits = ffs(data->blksz) - 1;
>         BUG_ON(1 << blksz_bits != data->blksz);
>
> +       moxart_init_sg(host, data);
> +
>         datactrl = DCR_DATA_EN | (blksz_bits & DCR_BLK_SIZE);
>
> -       if (data->flags & MMC_DATA_WRITE) {
> -               flags |= SG_MITER_FROM_SG;
> +       if (data->flags & MMC_DATA_WRITE)
>                 datactrl |= DCR_DATA_WRITE;
> -       } else {
> -               flags |= SG_MITER_TO_SG;
> -       }
>
>         if (moxart_use_dma(host))
>                 datactrl |= DCR_DMA_EN;
> -       else
> -               sg_miter_start(&host->sg_miter, data->sg, data->sg_len, flags);
>
>         writel(DCR_DATA_FIFO_RESET, host->base + REG_DATA_CONTROL);
>         writel(MASK_DATA | FIFO_URUN | FIFO_ORUN, host->base + REG_CLEAR);
> @@ -443,9 +454,6 @@ static void moxart_request(struct mmc_host *mmc, struct mmc_request *mrq)
>         }
>
>  request_done:
> -       if (!moxart_use_dma(host))
> -               sg_miter_stop(&host->sg_miter);
> -
>         spin_unlock_irqrestore(&host->lock, flags);
>         mmc_request_done(host->mmc, mrq);
>  }
>
> ---
> base-commit: 1613e604df0cd359cf2a7fbd9be7a0bcfacfabd0
> change-id: 20240606-mmc-moxart-revert-beb833b07dcb
>
> Best regards,
> --
> Linus Walleij <linus.walleij@linaro.org>
>