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author | Adrian Hunter <adrian.hunter@intel.com> | 2020-09-03 11:20:07 +0300 |
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committer | Ulf Hansson <ulf.hansson@linaro.org> | 2020-09-07 08:57:44 +0200 |
commit | f0c393e2104e48c8a881719a8bd37996f71b0aee (patch) | |
tree | a4db068d34f85435ab0926b42c518c1d68b21116 /drivers/mmc | |
parent | 060522d89705f9d961ef1762dc1468645dd21fbd (diff) | |
download | linux-f0c393e2104e48c8a881719a8bd37996f71b0aee.tar.gz linux-f0c393e2104e48c8a881719a8bd37996f71b0aee.tar.bz2 linux-f0c393e2104e48c8a881719a8bd37996f71b0aee.zip |
mmc: sdio: Use mmc_pre_req() / mmc_post_req()
SDHCI changed from using a tasklet to finish requests, to using an IRQ
thread i.e. commit c07a48c2651965 ("mmc: sdhci: Remove finish_tasklet").
Because this increased the latency to complete requests, a preparatory
change was made to complete the request from the IRQ handler if
possible i.e. commit 19d2f695f4e827 ("mmc: sdhci: Call mmc_request_done()
from IRQ handler if possible"). That alleviated the situation for MMC
block devices because the MMC block driver makes use of mmc_pre_req()
and mmc_post_req() so that successful requests are completed in the IRQ
handler and any DMA unmapping is handled separately in mmc_post_req().
However SDIO was still affected, and an example has been reported with
up to 20% degradation in performance.
Looking at SDIO I/O helper functions, sdio_io_rw_ext_helper() appeared
to be a possible candidate for making use of asynchronous requests
within its I/O loops, but analysis revealed that these loops almost
never iterate more than once, so the complexity of the change would not
be warrented.
Instead, mmc_pre_req() and mmc_post_req() are added before and after I/O
submission (mmc_wait_for_req) in mmc_io_rw_extended(). This still has
the potential benefit of reducing the duration of interrupt handlers, as
well as addressing the latency issue for SDHCI. It also seems a more
reasonable solution than forcing drivers to do everything in the IRQ
handler.
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Fixes: c07a48c2651965 ("mmc: sdhci: Remove finish_tasklet")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200903082007.18715-1-adrian.hunter@intel.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Diffstat (limited to 'drivers/mmc')
-rw-r--r-- | drivers/mmc/core/sdio_ops.c | 39 |
1 files changed, 22 insertions, 17 deletions
diff --git a/drivers/mmc/core/sdio_ops.c b/drivers/mmc/core/sdio_ops.c index 93d346c01110..4c229dd2b6e5 100644 --- a/drivers/mmc/core/sdio_ops.c +++ b/drivers/mmc/core/sdio_ops.c @@ -121,6 +121,7 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, struct sg_table sgtable; unsigned int nents, left_size, i; unsigned int seg_size = card->host->max_seg_size; + int err; WARN_ON(blksz == 0); @@ -170,28 +171,32 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, mmc_set_data_timeout(&data, card); - mmc_wait_for_req(card->host, &mrq); + mmc_pre_req(card->host, &mrq); - if (nents > 1) - sg_free_table(&sgtable); + mmc_wait_for_req(card->host, &mrq); if (cmd.error) - return cmd.error; - if (data.error) - return data.error; - - if (mmc_host_is_spi(card->host)) { + err = cmd.error; + else if (data.error) + err = data.error; + else if (mmc_host_is_spi(card->host)) /* host driver already reported errors */ - } else { - if (cmd.resp[0] & R5_ERROR) - return -EIO; - if (cmd.resp[0] & R5_FUNCTION_NUMBER) - return -EINVAL; - if (cmd.resp[0] & R5_OUT_OF_RANGE) - return -ERANGE; - } + err = 0; + else if (cmd.resp[0] & R5_ERROR) + err = -EIO; + else if (cmd.resp[0] & R5_FUNCTION_NUMBER) + err = -EINVAL; + else if (cmd.resp[0] & R5_OUT_OF_RANGE) + err = -ERANGE; + else + err = 0; - return 0; + mmc_post_req(card->host, &mrq, err); + + if (nents > 1) + sg_free_table(&sgtable); + + return err; } int sdio_reset(struct mmc_host *host) |