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SubjectRe: [PATCH RFC 2/2] mmc: meson-gx: use sg_copy_to/from_io instead of local version
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On 2021-06-28 13:34, Neil Armstrong wrote:
> Use the proper sg_copy_to_io & sg_copy_from_io instead of having a local
> sg_copy_buffer variant to handle the I/O mapped buffer case.
>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> ---
> drivers/mmc/host/meson-gx-mmc.c | 53 +++++++--------------------------
> 1 file changed, 10 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 3f28eb4d17fe..c13436efb414 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -746,47 +746,6 @@ 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);
> @@ -830,7 +789,12 @@ 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);
> - meson_mmc_copy_buffer(host, data, xfer_bytes, true);
> + if (host->dram_access_quirk)
> + sg_copy_to_io(data->sg, data->sg_len,
> + host->bounce_iomem_buf, xfer_bytes);

Maybe you could just use host->regs + SD_EMMC_SRAM_DATA_BUF_OFF directly
here (and below) and save carrying host->bounce_iomem_buf around?

Robin.

> + else
> + sg_copy_to_buffer(data->sg, data->sg_len,
> + host->bounce_buf, xfer_bytes);
> dma_wmb();
> }
>
> @@ -999,7 +963,10 @@ 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);
> - meson_mmc_copy_buffer(host, data, xfer_bytes, false);
> + if (host->dram_access_quirk)
> + sg_copy_from_io(data->sg, data->sg_len, host->bounce_iomem_buf, xfer_bytes);
> + else
> + sg_copy_from_buffer(data->sg, data->sg_len, host->bounce_buf, xfer_bytes);
> }
>
> next_cmd = meson_mmc_get_next_command(cmd);
>

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