[Linux-stm32] [PATCH 06/13] mmc: mmci: Make busy complete state machine explicit
Linus Walleij
linus.walleij at linaro.org
Wed Apr 5 06:50:32 UTC 2023
This refactors the ->busy_complete() callback currently
only used by Ux500 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 four states:
MMCI_BUSY_NOT_STARTED, MMCI_BUSY_WAITING_FOR_IRQS,
MMCI_BUSY_START_IRQ and MMCI_BUSY_END_IRQ.
The 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 dev_err() 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 at linaro.org>
---
drivers/mmc/host/mmci.c | 58 +++++++++++++++++++++++++++++++------
drivers/mmc/host/mmci.h | 16 ++++++++++
drivers/mmc/host/mmci_stm32_sdmmc.c | 6 +++-
3 files changed, 70 insertions(+), 10 deletions(-)
diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 13dec2e09164..c14a7732386e 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_IDLE) {
host->busy_status = status & (MCI_CMDSENT | MCI_CMDRESPEND);
status = readl(base + MMCISTATUS);
if (status & host->variant->busy_detect_flag) {
@@ -696,6 +697,7 @@ 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_IRQS;
return false;
}
}
@@ -711,11 +713,40 @@ 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_IRQS) {
+ 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_START_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 (host->busy_state == MMCI_BUSY_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_END_IRQ;
+ 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;
+ }
}
/*
@@ -724,11 +755,18 @@ static bool ux500_busy_complete(struct mmci_host *host, u32 status, u32 err_msk)
* 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);
+ if (host->busy_state == MMCI_BUSY_END_IRQ) {
+ if (status & host->variant->busy_detect_flag) {
+ /* We should just get two IRQs for busy detect */
+ dev_err(mmc_dev(host->mmc), "spurious busy detect IRQ\n");
+ return false;
+ }
+ 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;
}
@@ -1259,8 +1297,10 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c)
}
if (cmd->flags & MMC_RSP_BUSY) {
- if (host->ops->busy_complete)
+ if (host->ops->busy_complete) {
+ host->busy_state = MMCI_BUSY_IDLE;
host->busy_status = 0;
+ }
if (host->variant->busy_timeout) {
if (!cmd->busy_timeout)
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index e1a9b96a3396..82f3850325c8 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -261,6 +261,21 @@ 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_IDLE,
+ MMCI_BUSY_WAITING_FOR_IRQS,
+ MMCI_BUSY_START_IRQ,
+ MMCI_BUSY_END_IRQ,
+ MMCI_BUSY_DONE,
+};
+
/**
* struct variant_data - MMCI variant-specific quirks
* @clkreg: default value for MCICLOCK register
@@ -409,6 +424,7 @@ 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..24831a1092b2 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_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);
--
2.39.2
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