Some MMC/SD commands uses R1B responses, which means the card may assert the DAT0 line
to signal busy for a period of time, after it has received the command. The mmc
core normally specifies the busy period for the command in the
cmd->busy_timeout. Ideally the driver should respect it, but that isn't always
the case, for several reasons.
For example, the mmc host may not even support HW busy signal
detection, the HW may have a build-in upper limit of the timeout and the driver
simply uses that or it uses some other internal command/request SW timeout
mechanism with another timeout value.
In cases when the host driver can't support a cmd->busy_timeout, the core
implements a fallback method, which is based upon sending CMD13 to poll the card
about the status instead. However, to make this work, the host driver need to
specify the mmc->max_busy_timeout, as to make the core aware of when to use the
fallback method with CMD13 polling.
Step by step, host drivers has been improved to better cope with the above
scenarios. Although in this series, I have walked through *all* host drivers and
those that looked particularly suspicious I have fixed.
Note, none of the changes has been tested on HW, so I am relying on help with
this.
The next step beyond this series is to make MMC_CAP_ERASE default enabled, as
that would trigger CMD38 to be used. CMD38 uses the R1B response and may
typically require longer busy periods to be supported.
Kind regards
Ulf Hanssom
Ulf Hansson (19):
mmc: atmel-mci: Keep timer enabled when queuing a next request
mmc: atmel-mci: Set the timer per command rather than per request
mmc: atmel-mci: Respect the cmd->busy_timeout from the mmc core
mmc: jz4740: Inform the mmc core about the maximum busy timeout
mmc: usdhi6rol0: Inform the mmc core about the maximum busy timeout
mmc: cb710: Inform the mmc core about the maximum busy timeout
mmc: owl-mmc: Respect the cmd->busy_timeout from the mmc core
mmc: sdricoh_cs: Drop unused defines
mmc: sdricoh_cs: Use MMC_APP_CMD rather than a hardcoded number
mmc: sdricoh_cs: Move MMC_APP_CMD handling to sdricoh_mmc_cmd()
mmc: sdricoh_cs: Drop redundant in-parameter to sdricoh_query_status()
mmc: sdricoh_cs: Throttle polling rate for data transfers
mmc: sdricoh_cs: Throttle polling rate for commands
mmc: sdricoh_cs: Respect the cmd->busy_timeout from the mmc core
mmc: tifm_sd: Inform the mmc core about the maximum busy timeout
mmc: via-sdmmc: Respect the cmd->busy_timeout from the mmc core
mmc: mmc_spi: Add/rename defines for timeouts
mmc: mmc_spi: Respect the cmd->busy_timeout from the mmc core
staging: greybus: sdio: Respect the cmd->busy_timeout from the mmc
core
drivers/mmc/host/atmel-mci.c | 12 ++--
drivers/mmc/host/cb710-mmc.c | 8 +++
drivers/mmc/host/jz4740_mmc.c | 13 ++++-
drivers/mmc/host/mmc_spi.c | 20 +++----
drivers/mmc/host/owl-mmc.c | 8 ++-
drivers/mmc/host/sdricoh_cs.c | 103 +++++++++++++++++----------------
drivers/mmc/host/tifm_sd.c | 9 ++-
drivers/mmc/host/usdhi6rol0.c | 9 ++-
drivers/mmc/host/via-sdmmc.c | 7 ++-
drivers/staging/greybus/sdio.c | 10 +++-
10 files changed, 125 insertions(+), 74 deletions(-)
--
2.20.1
