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Subject[PATCH V3 2/2] mmc: mmci: send stop command to clear the dpsm
Date
From: Ludovic Barre <ludovic.barre@st.com>

The current approach with sending a CMD12 (STOP_TRANSMISSION) to
complete a data transfer request, either because of using the open
ended transmission type or because of receiving an error during a data
transfer, isn't sufficient for the STM32 sdmmc variant.

More precisely, for STM32 sdmmc the DPSM ("Data Path State Machine")
needs to be cleared by sending a CMD12, also for the so called ADTC
commands. For this reason, let the driver send a CMD12 to complete
ADTC commands, in case it's set (depend of cmdreg_stop variant property).

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
---
drivers/mmc/host/mmci.c | 37 +++++++++++++++++++++++++++++++++++++
drivers/mmc/host/mmci.h | 2 ++
2 files changed, 39 insertions(+)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index e352f5a..4e5643d 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -58,6 +58,8 @@ void sdmmc_variant_init(struct mmci_host *host);
#else
static inline void sdmmc_variant_init(struct mmci_host *host) {}
#endif
+static void
+mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c);

static unsigned int fmax = 515633;

@@ -572,9 +574,37 @@ void mmci_dma_error(struct mmci_host *host)
host->ops->dma_error(host);
}

+static int mmci_stop_command(struct mmci_host *host, struct mmc_request *mrq)
+{
+ u32 dpsm;
+
+ /*
+ * If an error happens on command or data transmission
+ * the DPSM stay enabled. The CPSM required a stop command
+ * to reinitialize the DPSM.
+ */
+ dpsm = readl_relaxed(host->base + MMCISTATUS);
+ dpsm &= MCI_STM32_DPSMACTIVE;
+
+ if (dpsm && ((mrq->cmd && mrq->cmd->error) ||
+ (mrq->data && mrq->data->error))) {
+ mmci_start_command(host, &host->stop_abort, 0);
+ return -EBUSY;
+ }
+
+ return 0;
+}
+
static void
mmci_request_end(struct mmci_host *host, struct mmc_request *mrq)
{
+ /*
+ * For variant with cmdstop bit, a stop command could be needed
+ * to finish the request.
+ */
+ if (host->variant->cmdreg_stop && mmci_stop_command(host, mrq))
+ return;
+
writel(0, host->base + MMCICOMMAND);

BUG_ON(host->data);
@@ -1956,6 +1986,13 @@ static int mmci_probe(struct amba_device *dev,
mmc->max_busy_timeout = 0;
}

+ /* prepare the stop command, used to abort and reinitialized the DPSM */
+ if (variant->cmdreg_stop) {
+ host->stop_abort.opcode = MMC_STOP_TRANSMISSION;
+ host->stop_abort.arg = 0;
+ host->stop_abort.flags = MMC_RSP_R1B | MMC_CMD_AC;
+ }
+
mmc->ops = &mmci_ops;

/* We support these PM capabilities. */
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 2422909..35372cd 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -161,6 +161,7 @@
#define MCI_ST_CEATAEND (1 << 23)
#define MCI_ST_CARDBUSY (1 << 24)
/* Extended status bits for the STM32 variants */
+#define MCI_STM32_DPSMACTIVE BIT(12)
#define MCI_STM32_BUSYD0 BIT(20)

#define MMCICLEAR 0x038
@@ -377,6 +378,7 @@ struct mmci_host {
void __iomem *base;
struct mmc_request *mrq;
struct mmc_command *cmd;
+ struct mmc_command stop_abort;
struct mmc_data *data;
struct mmc_host *mmc;
struct clk *clk;
--
2.7.4
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