This series fixes a pretty serious problem in the MMCI
busy detect handling, discovered only after going up and
down a ladder of refactorings.
The code is written expecting the Ux500 busy detect
to fire two interrupts: one at the start of the busy
signalling and one at the end of the busy signalling.
The root cause of the problem seen on some devices
is that only the first IRQ arrives, and then the device
hangs, waiting perpetually for the next IRQ to arrive.
This is eventually solved by adding a timeout using
a delayed work that fire after 10 ms if the busy detect
has not stopped at this point. (Other delay spans can
be suggested.) This is the last patch in the series.
I included the rewrite of the entire busy detect logic
to use a state machine as this makes it way easier to
debug and will print messages about other error
conditions as well.
The problem affects especially the Skomer
(Samsung GT-I9070) and Kyle (Samsung SGH-I407).
It is fine to just apply this for the -next kernel,
despite it fixes the busy detect that has been broken
for these devices for a while, we can think about
backporting a simpler version of the timeout for
stable kernels if we want.
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
Linus Walleij (13):
mmc: mmci: Only call busy_complete if callback defined
mmc: mmci: Clear busy_status when starting command
mmc: mmci: Unwind big if() clause
mmc: mmci: Stash status while waiting for busy
mmc: mmci: Break out error check in busy detect
mmc: mmci: Make busy complete state machine explicit
mmc: mmci: Retry the busy start condition
mmc: mmci: Use state machine state as exit condition
mmc: mmci: Use a switch statement machine
mmc: mmci: Break out a helper function
mmc: mmci: mmci_card_busy() from state machine
mmc: mmci: Drop end IRQ from Ux500 busydetect
mmc: mmci: Add busydetect timeout
drivers/mmc/host/mmci.c | 165 +++++++++++++++++++++++++++---------
drivers/mmc/host/mmci.h | 17 ++++
drivers/mmc/host/mmci_stm32_sdmmc.c | 6 +-
3 files changed, 149 insertions(+), 39 deletions(-)
---
base-commit: fe15c26ee26efa11741a7b632e9f23b01aca4cc6
change-id: 20230405-pl180-busydetect-fix-66a0360d398a
Best regards,
--
Linus Walleij <linus.walleij@xxxxxxxxxx>
