| Message ID | 20230405-pl180-busydetect-fix-v4-0-df9c8c504353@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Fix busydetect on Ux500 PL180/MMCI | expand |
On Tue, 13 Jun 2023 at 22:34, Linus Walleij <linus.walleij@linaro.org> wrote: > > 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 a timeout if the busy detect > has not stopped. 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@linaro.org> > --- > Changes in v4: > - Fix an unrelated change in patch 1 > - Move MMCI_BUSY_DONE initialization outside the if()-clause > for busy detection. > - Use the per-command ->busy_timeout as calculated by the > core. > - Link to v3: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v3-0-cd3d5925ae64@linaro.org > > Changes in v3: > - Unconditionally assign busy_status = 0 > - Rewrite state machine states to just three > - Drop a patch that gets absorbed into another patch > - Drop patch to get busy state from the state machine, it was > fishy, based on a misunderstanding and not needed > - Link to v2: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v2-0-eeb10323b546@linaro.org > > Changes in v2: > - Drop pointless patch nr 1 > - Unconditionally intialize some state variables > - Use a less fragile method to look for busy status when > using busy detect, should fix Yann's problem > - Link to v1: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v1-0-28ac19a74e5e@linaro.org > > --- > Linus Walleij (10): > 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: Add busydetect timeout > > drivers/mmc/host/mmci.c | 143 ++++++++++++++++++++++++++++-------- > drivers/mmc/host/mmci.h | 15 ++++ > drivers/mmc/host/mmci_stm32_sdmmc.c | 6 +- > 3 files changed, 132 insertions(+), 32 deletions(-) > --- > base-commit: 3dff3b32d4752f4a0655fad3c8669978c291ae59 > change-id: 20230405-pl180-busydetect-fix-66a0360d398a > > Best regards, > -- > Linus Walleij <linus.walleij@linaro.org> Applied patch1->patch9 for next, thanks! Let's continue to chat a bit more about patch10, to conclude. Kind regards Uffe
On Wed, Jun 14, 2023 at 12:32 PM Ulf Hansson <ulf.hansson@linaro.org> wrote: > Applied patch1->patch9 for next, thanks! Thanks! > Let's continue to chat a bit more about patch10, to conclude. Yeah that makes it much easier, iterating just one patch is less work :D Yours, Linus Walleij
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 a timeout if the busy detect has not stopped. 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@linaro.org> --- Changes in v4: - Fix an unrelated change in patch 1 - Move MMCI_BUSY_DONE initialization outside the if()-clause for busy detection. - Use the per-command ->busy_timeout as calculated by the core. - Link to v3: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v3-0-cd3d5925ae64@linaro.org Changes in v3: - Unconditionally assign busy_status = 0 - Rewrite state machine states to just three - Drop a patch that gets absorbed into another patch - Drop patch to get busy state from the state machine, it was fishy, based on a misunderstanding and not needed - Link to v2: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v2-0-eeb10323b546@linaro.org Changes in v2: - Drop pointless patch nr 1 - Unconditionally intialize some state variables - Use a less fragile method to look for busy status when using busy detect, should fix Yann's problem - Link to v1: https://lore.kernel.org/r/20230405-pl180-busydetect-fix-v1-0-28ac19a74e5e@linaro.org --- Linus Walleij (10): 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: Add busydetect timeout drivers/mmc/host/mmci.c | 143 ++++++++++++++++++++++++++++-------- drivers/mmc/host/mmci.h | 15 ++++ drivers/mmc/host/mmci_stm32_sdmmc.c | 6 +- 3 files changed, 132 insertions(+), 32 deletions(-) --- base-commit: 3dff3b32d4752f4a0655fad3c8669978c291ae59 change-id: 20230405-pl180-busydetect-fix-66a0360d398a Best regards,