On Thu, 31 Mar 2022 at 09:32, Michael Wu <michael@xxxxxxxxxxxxxxxxx> wrote:
>
> The mmc core enables cache by default. But it only enables
> cache-flushing when host supports cmd23 and eMMC supports
> reliable-write.
> For hosts which do not support cmd23 or eMMCs which do not support
> reliable-write, the cache can not be flushed by `sync` command.
> This may leads to cache data lost.
> This patch enables cache-flushing as long as cache is enabled,
> no matter host supports cmd23 and/or eMMC supports reliable write
> or not.
> For SD cards, backwards compatibility is guaranteed. Newer components
> like SD5.0 which have cache are also supported in advance, which means
> this patch will also be applicable if SD5.0 cache is added to the mmc
> core in the future.
SD 5.0 cache support was added in the commit 130206a615a9 below. No
need to resend, I will take care of updating the commit message.
>
> Fixes: f4c5522b0a88 ("mmc: Reliable write support.")
> Fixes: 881d1c25f765 ("mmc: core: Add cache control for eMMC4.5 device")
> Fixes: 130206a615a9 ("mmc: core: Add support for cache ctrl for SD cards")
> Fixes: d0c97cfb81eb ("mmc: core: Use CMD23 for multiblock transfers when we can.")
> Fixes: e9d5c746246c ("mmc/block: switch to using blk_queue_write_cache()")
I will have a look at the above to see what makes sense to add - and
then I will add a stable tag too.
>
> Reviewed-by: Avri Altman <Avri.Altman@xxxxxxx>
> Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>
> Signed-off-by: Michael Wu <michael@xxxxxxxxxxxxxxxxx>
Thanks, applied for fixes!
Kind regards
Uffe
> ---
> drivers/mmc/core/block.c | 12 +++++++++---
> 1 file changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 4e67c1403cc9..ec76ed82abb9 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -2350,6 +2350,8 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
> struct mmc_blk_data *md;
> int devidx, ret;
> char cap_str[10];
> + bool cache_enabled = false;
> + bool fua_enabled = false;
>
> devidx = ida_simple_get(&mmc_blk_ida, 0, max_devices, GFP_KERNEL);
> if (devidx < 0) {
> @@ -2429,13 +2431,17 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
> md->flags |= MMC_BLK_CMD23;
> }
>
> - if (mmc_card_mmc(card) &&
> - md->flags & MMC_BLK_CMD23 &&
> + if (md->flags & MMC_BLK_CMD23 &&
> ((card->ext_csd.rel_param & EXT_CSD_WR_REL_PARAM_EN) ||
> card->ext_csd.rel_sectors)) {
> md->flags |= MMC_BLK_REL_WR;
> - blk_queue_write_cache(md->queue.queue, true, true);
> + fua_enabled = true;
> + cache_enabled = true;
> }
> + if (mmc_cache_enabled(card->host))
> + cache_enabled = true;
> +
> + blk_queue_write_cache(md->queue.queue, cache_enabled, fua_enabled);
>
> string_get_size((u64)size, 512, STRING_UNITS_2,
> cap_str, sizeof(cap_str));
> --
> 2.29.0
>
