| Message ID | 20230405-pl180-busydetect-fix-v4-5-df9c8c504353@linaro.org |
|---|---|
| State | Superseded |
| 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 refactors the ->busy_complete() callback currently > only used by Ux500 and STM32 to handle busy detection on > hardware where one and the same IRQ is fired whether we get > a start or an end signal on busy detect. > > The code is currently using the cached status from the > command IRQ in ->busy_status as a state to select what to > do next: if this state is non-zero we are waiting for > IRQs and if it is zero we treat the state as the starting > point for a busy detect wait cycle. > > Make this explicit by creating a state machine where the > ->busy_complete callback moves between three states. > > The Ux500 busy detect code currently assumes this order: > we enable the busy detect IRQ, get a busy start IRQ, then a > busy end IRQ, and then we clear and mask this IRQ and > proceed. > > We insert debug prints for unexpected states. > > Augment the STM32 driver with similar states for > completeness. > > This works as before on most cards, however on a > problematic card that is not working with busy detect, and > which I have been debugging, this happens: > > [127220.662719] mmci-pl18x 80005000.mmc: lost busy status > when waiting for busy end IRQ > > This probably means that the busy detect start IRQ has > already occurred when we start executing the > ->busy_complete() callbacks, and the busy detect end IRQ > is counted as the start IRQ, and this is what is causing > the card to not be detected properly. > > Signed-off-by: Linus Walleij <linus.walleij@linaro.org> > --- > ChangeLog v3->v4: > - Assign state MMCI_BUSY_DONE outside the if()-clause for > the busy detect initialization. > ChangeLog v2->v3: > - Drop surplus states and merge IDLE and DONE states into one, > we start out DONE. Name states *_WAITING_FOR_* so it is clear > what is going on. > - Rebase on other changes. > - Reword commit message. > ChangeLog v1->v2: > - No changes > --- > drivers/mmc/host/mmci.c | 55 +++++++++++++++++++++++++------------ > drivers/mmc/host/mmci.h | 14 ++++++++++ > drivers/mmc/host/mmci_stm32_sdmmc.c | 6 +++- > 3 files changed, 56 insertions(+), 19 deletions(-) > > diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c > index d632658d9d20..3b1a23e4ec1c 100644 > --- a/drivers/mmc/host/mmci.c > +++ b/drivers/mmc/host/mmci.c > @@ -670,6 +670,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) > writel(host->variant->busy_detect_mask, base + MMCICLEAR); > writel(readl(base + MMCIMASK0) & > ~host->variant->busy_detect_mask, base + MMCIMASK0); > + host->busy_state = MMCI_BUSY_DONE; > host->busy_status = 0; > return true; > } > @@ -687,7 +688,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) > * while, to allow it to be set, but tests indicates that it > * isn't needed. > */ > - if (!host->busy_status) { > + if (host->busy_state == MMCI_BUSY_DONE) { > status = readl(base + MMCISTATUS); > if (status & host->variant->busy_detect_flag) { > writel(readl(base + MMCIMASK0) | > @@ -695,6 +696,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) > base + MMCIMASK0); > > host->busy_status = status & (MCI_CMDSENT | MCI_CMDRESPEND); > + host->busy_state = MMCI_BUSY_WAITING_FOR_START_IRQ; > return false; > } > } > @@ -710,25 +712,40 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) > * both the start and the end interrupts needs to be cleared, > * one after the other. So, clear the busy start IRQ here. > */ > - if (host->busy_status && > - (status & host->variant->busy_detect_flag)) { > - host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); > - writel(host->variant->busy_detect_mask, base + MMCICLEAR); > - return false; > + if (host->busy_state == MMCI_BUSY_WAITING_FOR_START_IRQ) { > + if (status & host->variant->busy_detect_flag) { > + host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); > + writel(host->variant->busy_detect_mask, base + MMCICLEAR); > + host->busy_state = MMCI_BUSY_WAITING_FOR_END_IRQ; > + return false; > + } else { > + dev_dbg(mmc_dev(host->mmc), > + "lost busy status when waiting for busy start IRQ\n"); > + writel(host->variant->busy_detect_mask, base + MMCICLEAR); > + writel(readl(base + MMCIMASK0) & > + ~host->variant->busy_detect_mask, base + MMCIMASK0); > + host->busy_state = MMCI_BUSY_DONE; > + host->busy_status = 0; > + return true; > + } > } > > - /* > - * If there is a command in-progress that has been successfully > - * sent and the busy bit isn't set, it means we have received > - * the busy end IRQ. Clear and mask the IRQ, then continue to > - * process the command. > - */ > - if (host->busy_status) { > - writel(host->variant->busy_detect_mask, base + MMCICLEAR); > - > - writel(readl(base + MMCIMASK0) & > - ~host->variant->busy_detect_mask, base + MMCIMASK0); > - host->busy_status = 0; > + if (host->busy_state == MMCI_BUSY_WAITING_FOR_END_IRQ) { > + if (status & host->variant->busy_detect_flag) { I realize that I have already queued up $subject patch, but I haven't been able to test this myself yet. However, I wonder if the above is really correct? More precisely, did you confirm that the variant->busy_detect_flag-bit becomes set for the ux500 variant, when the card stops signaling busy? If not, we will always end up in the else clause below? > + host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); > + writel(host->variant->busy_detect_mask, base + MMCICLEAR); > + host->busy_state = MMCI_BUSY_DONE; > + return false; > + } else { > + dev_dbg(mmc_dev(host->mmc), > + "lost busy status when waiting for busy end IRQ\n"); > + writel(host->variant->busy_detect_mask, base + MMCICLEAR); > + writel(readl(base + MMCIMASK0) & > + ~host->variant->busy_detect_mask, base + MMCIMASK0); > + host->busy_state = MMCI_BUSY_DONE; > + host->busy_status = 0; > + return true; > + } > } > [...] Kind regards Uffe
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c index d632658d9d20..3b1a23e4ec1c 100644 --- a/drivers/mmc/host/mmci.c +++ b/drivers/mmc/host/mmci.c @@ -670,6 +670,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) writel(host->variant->busy_detect_mask, base + MMCICLEAR); writel(readl(base + MMCIMASK0) & ~host->variant->busy_detect_mask, base + MMCIMASK0); + host->busy_state = MMCI_BUSY_DONE; host->busy_status = 0; return true; } @@ -687,7 +688,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) * while, to allow it to be set, but tests indicates that it * isn't needed. */ - if (!host->busy_status) { + if (host->busy_state == MMCI_BUSY_DONE) { status = readl(base + MMCISTATUS); if (status & host->variant->busy_detect_flag) { writel(readl(base + MMCIMASK0) | @@ -695,6 +696,7 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) base + MMCIMASK0); host->busy_status = status & (MCI_CMDSENT | MCI_CMDRESPEND); + host->busy_state = MMCI_BUSY_WAITING_FOR_START_IRQ; return false; } } @@ -710,25 +712,40 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) * both the start and the end interrupts needs to be cleared, * one after the other. So, clear the busy start IRQ here. */ - if (host->busy_status && - (status & host->variant->busy_detect_flag)) { - host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); - writel(host->variant->busy_detect_mask, base + MMCICLEAR); - return false; + if (host->busy_state == MMCI_BUSY_WAITING_FOR_START_IRQ) { + if (status & host->variant->busy_detect_flag) { + host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); + writel(host->variant->busy_detect_mask, base + MMCICLEAR); + host->busy_state = MMCI_BUSY_WAITING_FOR_END_IRQ; + return false; + } else { + dev_dbg(mmc_dev(host->mmc), + "lost busy status when waiting for busy start IRQ\n"); + writel(host->variant->busy_detect_mask, base + MMCICLEAR); + writel(readl(base + MMCIMASK0) & + ~host->variant->busy_detect_mask, base + MMCIMASK0); + host->busy_state = MMCI_BUSY_DONE; + host->busy_status = 0; + return true; + } } - /* - * If there is a command in-progress that has been successfully - * sent and the busy bit isn't set, it means we have received - * the busy end IRQ. Clear and mask the IRQ, then continue to - * process the command. - */ - if (host->busy_status) { - writel(host->variant->busy_detect_mask, base + MMCICLEAR); - - writel(readl(base + MMCIMASK0) & - ~host->variant->busy_detect_mask, base + MMCIMASK0); - host->busy_status = 0; + if (host->busy_state == MMCI_BUSY_WAITING_FOR_END_IRQ) { + if (status & host->variant->busy_detect_flag) { + host->busy_status |= status & (MCI_CMDSENT | MCI_CMDRESPEND); + writel(host->variant->busy_detect_mask, base + MMCICLEAR); + host->busy_state = MMCI_BUSY_DONE; + return false; + } else { + dev_dbg(mmc_dev(host->mmc), + "lost busy status when waiting for busy end IRQ\n"); + writel(host->variant->busy_detect_mask, base + MMCICLEAR); + writel(readl(base + MMCIMASK0) & + ~host->variant->busy_detect_mask, base + MMCIMASK0); + host->busy_state = MMCI_BUSY_DONE; + host->busy_status = 0; + return true; + } } return true; @@ -1258,6 +1275,8 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c) } host->busy_status = 0; + host->busy_state = MMCI_BUSY_DONE; + if (host->variant->busy_timeout && cmd->flags & MMC_RSP_BUSY) { if (!cmd->busy_timeout) cmd->busy_timeout = 10 * MSEC_PER_SEC; diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h index e1a9b96a3396..12a7bbd3ce26 100644 --- a/drivers/mmc/host/mmci.h +++ b/drivers/mmc/host/mmci.h @@ -261,6 +261,19 @@ struct clk; struct dma_chan; struct mmci_host; +/** + * enum mmci_busy_state - enumerate the busy detect wait states + * + * This is used for the state machine waiting for different busy detect + * interrupts on hardware that fire a single IRQ for start and end of + * the busy detect phase on DAT0. + */ +enum mmci_busy_state { + MMCI_BUSY_WAITING_FOR_START_IRQ, + MMCI_BUSY_WAITING_FOR_END_IRQ, + MMCI_BUSY_DONE, +}; + /** * struct variant_data - MMCI variant-specific quirks * @clkreg: default value for MCICLOCK register @@ -409,6 +422,7 @@ struct mmci_host { u32 clk_reg; u32 clk_reg_add; u32 datactrl_reg; + enum mmci_busy_state busy_state; u32 busy_status; u32 mask1_reg; u8 vqmmc_enabled:1; diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c index 60bca78a72b1..a805647b6664 100644 --- a/drivers/mmc/host/mmci_stm32_sdmmc.c +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c @@ -393,8 +393,10 @@ static bool sdmmc_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) busy_d0 = sdmmc_status & MCI_STM32_BUSYD0; /* complete if there is an error or busy_d0end */ - if ((status & err_msk) || busy_d0end) + if ((status & err_msk) || busy_d0end) { + host->busy_state = MMCI_BUSY_DONE; goto complete; + } /* * On response the busy signaling is reflected in the BUSYD0 flag. @@ -408,6 +410,7 @@ static bool sdmmc_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) host->busy_status = status & (MCI_CMDSENT | MCI_CMDRESPEND); } + host->busy_state = MMCI_BUSY_WAITING_FOR_END_IRQ; return false; } @@ -416,6 +419,7 @@ static bool sdmmc_busy_complete(struct mmci_host *host, u32 status, u32 err_msk) writel_relaxed(mask & ~host->variant->busy_detect_mask, base + MMCIMASK0); host->busy_status = 0; + host->busy_state = MMCI_BUSY_DONE; } writel_relaxed(host->variant->busy_detect_mask, base + MMCICLEAR);
This refactors the ->busy_complete() callback currently only used by Ux500 and STM32 to handle busy detection on hardware where one and the same IRQ is fired whether we get a start or an end signal on busy detect. The code is currently using the cached status from the command IRQ in ->busy_status as a state to select what to do next: if this state is non-zero we are waiting for IRQs and if it is zero we treat the state as the starting point for a busy detect wait cycle. Make this explicit by creating a state machine where the ->busy_complete callback moves between three states. The Ux500 busy detect code currently assumes this order: we enable the busy detect IRQ, get a busy start IRQ, then a busy end IRQ, and then we clear and mask this IRQ and proceed. We insert debug prints for unexpected states. Augment the STM32 driver with similar states for completeness. This works as before on most cards, however on a problematic card that is not working with busy detect, and which I have been debugging, this happens: [127220.662719] mmci-pl18x 80005000.mmc: lost busy status when waiting for busy end IRQ This probably means that the busy detect start IRQ has already occurred when we start executing the ->busy_complete() callbacks, and the busy detect end IRQ is counted as the start IRQ, and this is what is causing the card to not be detected properly. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- ChangeLog v3->v4: - Assign state MMCI_BUSY_DONE outside the if()-clause for the busy detect initialization. ChangeLog v2->v3: - Drop surplus states and merge IDLE and DONE states into one, we start out DONE. Name states *_WAITING_FOR_* so it is clear what is going on. - Rebase on other changes. - Reword commit message. ChangeLog v1->v2: - No changes --- drivers/mmc/host/mmci.c | 55 +++++++++++++++++++++++++------------ drivers/mmc/host/mmci.h | 14 ++++++++++ drivers/mmc/host/mmci_stm32_sdmmc.c | 6 +++- 3 files changed, 56 insertions(+), 19 deletions(-)