Re: [PATCH] mmc: meson-gx: use memcpy_to/fromio for dram-access-quirk

---
 drivers/mmc/host/meson-gx-mmc.c | 50 +++++++++++++++++++++++++++++----
 1 file changed, 45 insertions(+), 5 deletions(-)


Changes since RFC:
- moved iomem address to bounce_iomem_buf otherwise sparse screamed when feeding memcpy_to/fromio with non iomem pointer

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index b8b771b643cc..3e9b28f18c70 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c

@@ -165,6 +165,7 @@ struct meson_host {

        unsigned int bounce_buf_size;
        void *bounce_buf;
+       void __iomem *bounce_iomem_buf;
        dma_addr_t bounce_dma_addr;
        struct sd_emmc_desc *descs;
        dma_addr_t descs_dma_addr;

@@ -742,6 +743,47 @@ static void meson_mmc_desc_chain_transfer(struct mmc_host *mmc, u32 cmd_cfg)
        writel(start, host->regs + SD_EMMC_START);
 }

+/* local sg copy to buffer version with _to/fromio usage for dram_access_quirk */
+static void meson_mmc_copy_buffer(struct meson_host *host, struct mmc_data *data,
+                                 size_t buflen, bool to_buffer)
+{
+       unsigned int sg_flags = SG_MITER_ATOMIC;
+       struct scatterlist *sgl = data->sg;
+       unsigned int nents = data->sg_len;
+       struct sg_mapping_iter miter;
+       unsigned int offset = 0;
+
+       if (to_buffer)
+               sg_flags |= SG_MITER_FROM_SG;
+       else
+               sg_flags |= SG_MITER_TO_SG;
+
+       sg_miter_start(&miter, sgl, nents, sg_flags);
+
+       while ((offset < buflen) && sg_miter_next(&miter)) {
+               unsigned int len;
+
+               len = min(miter.length, buflen - offset);
+
+               /* When dram_access_quirk, the bounce buffer is a iomem mapping */
+               if (host->dram_access_quirk) {
+                       if (to_buffer)
+                               memcpy_toio(host->bounce_iomem_buf + offset, miter.addr, len);
+                       else
+                               memcpy_fromio(miter.addr, host->bounce_iomem_buf + offset, len);
+               } else {
+                       if (to_buffer)
+                               memcpy(host->bounce_buf + offset, miter.addr, len);
+                       else
+                               memcpy(miter.addr, host->bounce_buf + offset, len);
+               }
+
+               offset += len;
+       }
+
+       sg_miter_stop(&miter);
+}
+
 static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
 {
        struct meson_host *host = mmc_priv(mmc);

@@ -785,8 +827,7 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd)
                if (data->flags & MMC_DATA_WRITE) {
                        cmd_cfg |= CMD_CFG_DATA_WR;
                        WARN_ON(xfer_bytes > host->bounce_buf_size);
-                       sg_copy_to_buffer(data->sg, data->sg_len,
-                                         host->bounce_buf, xfer_bytes);
+                       meson_mmc_copy_buffer(host, data, xfer_bytes, true);
                        dma_wmb();
                }

@@ -955,8 +996,7 @@ static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
        if (meson_mmc_bounce_buf_read(data)) {
                xfer_bytes = data->blksz * data->blocks;
                WARN_ON(xfer_bytes > host->bounce_buf_size);
-               sg_copy_from_buffer(data->sg, data->sg_len,
-                                   host->bounce_buf, xfer_bytes);
+               meson_mmc_copy_buffer(host, data, xfer_bytes, false);
        }

        next_cmd = meson_mmc_get_next_command(cmd);

@@ -1176,7 +1216,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
                 * instead of the DDR memory
                 */
                host->bounce_buf_size = SD_EMMC_SRAM_DATA_BUF_LEN;
-               host->bounce_buf = host->regs + SD_EMMC_SRAM_DATA_BUF_OFF;
+               host->bounce_iomem_buf = host->regs + SD_EMMC_SRAM_DATA_BUF_OFF;
                host->bounce_dma_addr = res->start + SD_EMMC_SRAM_DATA_BUF_OFF;
        } else {
                /* data bounce buffer */
--

2.25.1