[PATCH rtems-libbsd 2/2] st-sdmmc: Handle short not cache aligned buffers

[Gedare Bloom]

These two look good if no one complains go ahead. (I'm not 100% on
this libbsd stuff yet.)

On Wed, Apr 14, 2021 at 1:21 AM Christian Mauderer
<christian.mauderer at embedded-brains.de> wrote:
>
> Possible data sources for SD driver:
>
> - mmc_sd_switch():
>     - length: 64 byte;
>     - buffer on stack
> - mmc_test_bus_width():
>     - length: 4 or 8 byte
>     - buffer in program memory or on stack
> - mmc_app_send_scr():
>     - length: 8 byte
>     - buffer from device ivar structure
> - mmc_app_sd_status():
>     - length: 64 byte
>     - buffer from device ivar structure
> - mmc_send_ext_csd():
>     - length: MMC_EXTCSD_SIZE = 512
>     - buffer from device ivar structure
> - rtems_bsd_mmcsd_disk_read_write():
>     - length: depends on read
>     - buffer from rtems_blkdev buffer -> already aligned
> - mmcsd_ioctl_cmd():
>     - length: depends on call
>     - buffer malloced, not aligned -> patched in RTEMS
>
> So the problematic buffers are only the ones up to 512 bytes. Copy these data
> into a buffer to avoid that problem.
> ---
>  rtemsbsd/sys/dev/mmc/st-sdmmc.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/rtemsbsd/sys/dev/mmc/st-sdmmc.c b/rtemsbsd/sys/dev/mmc/st-sdmmc.c
> index e50b400a..4b202952 100644
> --- a/rtemsbsd/sys/dev/mmc/st-sdmmc.c
> +++ b/rtemsbsd/sys/dev/mmc/st-sdmmc.c
> @@ -117,7 +117,8 @@ __FBSDID("$FreeBSD$");
>  #define RES_IRQ_SDMMC 2
>  #define RES_NR 3
>
> -#define DMA_BUF_SIZE CPU_CACHE_LINE_BYTES
> +/* Maximum non-aligned buffer is 512 byte from mmc_send_ext_csd() */
> +#define DMA_BUF_SIZE 512
>
>  #if 0
>  #define debug_print(sc, lvl, ...) \
> @@ -575,14 +576,19 @@ st_sdmmc_cmd_do(struct st_sdmmc_softc *sc, struct mmc_command *cmd)
>
>                 BSD_ASSERT(xferlen % (1 << blksize) == 0);
>
> -               if (xferlen < CPU_CACHE_LINE_BYTES) {
> +               data = cmd->data->data;
> +               /*
> +                * Check whether data have to be copied. Reason is either
> +                * misaligned start address or misaligned length.
> +                */
> +               if (((uintptr_t)data % CPU_CACHE_LINE_BYTES != 0) ||
> +                   (xferlen % CPU_CACHE_LINE_BYTES) != 0) {
> +                       BSD_ASSERT(xferlen < DMA_BUF_SIZE);
>                         if ((cmd->data->flags & MMC_DATA_READ) == 0) {
>                                 memcpy(sc->dmabuf, cmd->data->data, xferlen);
>                         }
>                         data = sc->dmabuf;
>                         short_xfer = true;
> -               } else {
> -                       data = cmd->data->data;
>                 }
>
>                 dctrl |= blksize << SDMMC_DCTRL_DBLOCKSIZE_Pos;
> --
> 2.26.2
>
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