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>
Fixes: 3ee0e7c3e67c ("mmc: moxart-mmc: Use sg_miter for PIO")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240606-mmc-moxart-revert-v1-1-a01c2f40de9c@linaro.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/moxart-mmc.c b/drivers/mmc/host/moxart-mmc.c
index 9a5f75163acaeef8226ee122dde79c60fd9b7d8c..8ede4ce9327149b87eef0df976081644d982b80c 100644 (file)
--- 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);
 }