On Thu, Aug 26, 2021 at 08:59:53PM +0900, Nobuhiro Iwamatsu wrote:
Hi,
2021年8月25日(水) 2:39 Sasha Levin sashal@kernel.org:
From: Doug Anderson dianders@chromium.org
[ Upstream commit 46d179525a1f6d16957dcb4624517bc04142b3e7 ]
According to the DesignWare state machine description, after we get a "response error" or "response CRC error" we move into data transfer mode. That means that we don't necessarily need to special case trying to deal with the failure right away. We can wait until we are notified that the data transfer is complete (with or without errors) and then we can deal with the failure.
It may sound strange to defer dealing with a command that we know will fail anyway, but this appears to fix a bug. During tuning (CMD19) on a specific card on an rk3288-based system, we found that we could get a "response CRC error". Sending the stop command after the "response CRC error" would then throw the system into a confused state causing all future tuning phases to report failure.
When in the confused state, the controller would show these (hex codes are interrupt status register): CMD ERR: 0x00000046 (cmd=19) CMD ERR: 0x0000004e (cmd=12) DATA ERR: 0x00000208 DATA ERR: 0x0000020c CMD ERR: 0x00000104 (cmd=19) CMD ERR: 0x00000104 (cmd=12) DATA ERR: 0x00000208 DATA ERR: 0x0000020c ... ...
It is inherently difficult to deal with the complexity of trying to correctly send a stop command while a data transfer is taking place since you need to deal with different corner cases caused by the fact that the data transfer could complete (with errors or without errors) during various places in sending the stop command (dw_mci_stop_dma, send_stop_abort, etc)
Instead of adding a bunch of extra complexity to deal with this, it seems much simpler to just use the more straightforward (and less error-prone) path of letting the data transfer finish. There shouldn't be any huge benefit to sending the stop command slightly earlier, anyway.
Signed-off-by: Doug Anderson dianders@chromium.org Signed-off-by: Enric Balletbo i Serra enric.balletbo@collabora.com Cc: Alim Akhtar alim.akhtar@gmail.com Signed-off-by: Jaehoon Chung jh80.chung@samsung.com Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org
This commit also requires the following modifications: ba2d139b02ba68: mmc: dw_mmc: Fix occasional hang after tuning on eMMC
Please apply this commit too.
Will do, thanks!