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authorDaniel Drake <drake@endlessm.com>2019-03-26 15:04:14 +0800
committerUlf Hansson <ulf.hansson@linaro.org>2019-03-28 13:42:15 +0100
commit157c99c5a2956a9ab1ae12de0136a2d8a1b1a307 (patch)
tree35a06018a5085a92d2e9849f5885f03197da1b7a /COPYING
parent8c2ffd9174779014c3fe1f96d9dc3641d9175f00 (diff)
mmc: alcor: don't write data before command has completed
The alcor driver is setting up data transfer and submitting the associated MMC command at the same time. While this works most of the time, it occasionally causes problems upon write. In the working case, after setting up the data transfer and submitting the MMC command, an interrupt comes in a moment later with CMD_END and WRITE_BUF_RDY bits set. The data transfer then happens without problem. However, on occasion, the interrupt that arrives at that point only has WRITE_BUF_RDY set. The hardware notifies that it's ready to write data, but the associated MMC command is still running. Regardless, the driver was proceeding to write data immediately, and that would then cause another interrupt indicating data CRC error, and the write would fail. Additionally, the transfer setup function alcor_trigger_data_transfer() was being called 3 times for each write operation, which was confusing and may be contributing to this issue. Solve this by tweaking the driver behaviour to follow the sequence observed in the original ampe_stor vendor driver: 1. When starting request handling, write 0 to DATA_XFER_CTRL 2. Submit the command 3. Wait for CMD_END interrupt and then trigger data transfer 4. For the PIO case, trigger the next step of the data transfer only upon the following DATA_END interrupt, which occurs after the block has been written. I confirmed that the read path still works (DMA & PIO) and also now presents more consistency with the operations performed by ampe_stor. Signed-off-by: Daniel Drake <drake@endlessm.com> Fixes: c5413ad815a6 ("mmc: add new Alcor Micro Cardreader SD/MMC driver") Cc: stable@vger.kernel.org Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
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