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Subject[PATCH] mmc: mmci: add variant property to send stop cmd if a command fail
Date
From: Ludovic Barre <ludovic.barre@st.com>

The mmc framework follows the requirement of SD_Specification:
the STOP_TRANSMISSION is sent on multiple write/read commands
and the stop command (alone), not needed on other ADTC commands.

But, if an error happens on command or data step, some variants
require a stop command "STOP_TRANSMISION" to clear the DPSM
"Data Path State Machine". If it's not done the next data
command freezes hardware block.
Needed to support the STM32 sdmmc variant.

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
---
drivers/mmc/host/mmci.c | 33 +++++++++++++++++++++++++++++++++
drivers/mmc/host/mmci.h | 4 ++++
2 files changed, 37 insertions(+)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 19650ed..ecedca3 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -21,6 +21,7 @@
#include <linux/err.h>
#include <linux/highmem.h>
#include <linux/log2.h>
+#include <linux/mmc/mmc.h>
#include <linux/mmc/pm.h>
#include <linux/mmc/host.h>
#include <linux/mmc/card.h>
@@ -57,6 +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;

@@ -274,6 +277,7 @@ static struct variant_data variant_stm32_sdmmc = {
.cmdreg_lrsp_crc = MCI_CPSM_STM32_LRSP_CRC,
.cmdreg_srsp_crc = MCI_CPSM_STM32_SRSP_CRC,
.cmdreg_srsp = MCI_CPSM_STM32_SRSP,
+ .cmdreg_stop = MCI_CPSM_STM32_CMDSTOP,
.data_cmd_enable = MCI_CPSM_STM32_CMDTRANS,
.irq_pio_mask = MCI_IRQ_PIO_STM32_MASK,
.datactrl_first = true,
@@ -574,6 +578,24 @@ void mmci_dma_error(struct mmci_host *host)
static void
mmci_request_end(struct mmci_host *host, struct mmc_request *mrq)
{
+ /*
+ * If an error happens on command or data step, some variants
+ * require a stop command to reinit the DPSM.
+ * If it's not done the next data command freeze hardware block.
+ */
+ if (host->variant->cmdreg_stop) {
+ u32 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;
+ }
+ }
+
writel(0, host->base + MMCICOMMAND);

BUG_ON(host->data);
@@ -1106,6 +1128,10 @@ mmci_start_command(struct mmci_host *host, struct mmc_command *cmd, u32 c)
mmci_reg_delay(host);
}

+ if (host->variant->cmdreg_stop &&
+ cmd->opcode == MMC_STOP_TRANSMISSION)
+ c |= host->variant->cmdreg_stop;
+
c |= cmd->opcode | host->variant->cmdreg_cpsm_enable;
if (cmd->flags & MMC_RSP_PRESENT) {
if (cmd->flags & MMC_RSP_136)
@@ -1957,6 +1983,13 @@ 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 ec13d90..afb6ec4 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -166,6 +166,7 @@
#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
@@ -269,6 +270,7 @@ struct mmci_host;
* @cmdreg_lrsp_crc: enable value for long response with crc
* @cmdreg_srsp_crc: enable value for short response with crc
* @cmdreg_srsp: enable value for short response without crc
+ * @cmdreg_stop: enable value for stop and abort transmission
* @datalength_bits: number of bits in the MMCIDATALENGTH register
* @fifosize: number of bytes that can be written when MMCI_TXFIFOEMPTY
* is asserted (likewise for RX)
@@ -322,6 +324,7 @@ struct variant_data {
unsigned int cmdreg_lrsp_crc;
unsigned int cmdreg_srsp_crc;
unsigned int cmdreg_srsp;
+ unsigned int cmdreg_stop;
unsigned int datalength_bits;
unsigned int fifosize;
unsigned int fifohalfsize;
@@ -384,6 +387,7 @@ 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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