From: Ludovic Barre <[email protected]>

This patch adds a boolean property to not read datacnt register.
Needed to support the STM32 sdmmc variant. MMCIDATACNT
register should be read only after the data transfer is completed.
When reading after an error event the read data count value may be
different from the real number of data bytes transferred.

Signed-off-by: Ludovic Barre <[email protected]>
---
 drivers/mmc/host/mmci.c | 8 ++++++--
 drivers/mmc/host/mmci.h | 3 +++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index b525ba4..b1d5bc5 100644
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -1095,8 +1095,12 @@ mmci_data_irq(struct mmci_host *host, struct mmc_data 
*data,
                 * can be as much as a FIFO-worth of data ahead.  This
                 * matters for FIFO overruns only.
                 */
-               remain = readl(host->base + MMCIDATACNT);
-               success = data->blksz * data->blocks - remain;
+               if (!host->variant->datacnt_useless) {
+                       remain = readl(host->base + MMCIDATACNT);
+                       success = data->blksz * data->blocks - remain;
+               } else {
+                       success = 0;
+               }
 
                dev_dbg(mmc_dev(host->mmc), "MCI ERROR IRQ, status 0x%08x at 
0x%08x\n",
                        status_err, success);
diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 89e6733..7fd89b7 100644
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -224,6 +224,8 @@ struct mmci_host;
  * @datactrl_blksz: block size in power of two
  * @datactrl_dpsm_enable: enable value for DPSM
  * @datactrl_first: true if data must be setup before send command
+ * @datacnt_useless: true if you could not use datacnt register to read
+ *                  remaining data
  * @pwrreg_powerup: power up value for MMCIPOWER register
  * @f_max: maximum clk frequency supported by the controller.
  * @signal_direction: input/out direction of bus signals can be indicated
@@ -264,6 +266,7 @@ struct variant_data {
        unsigned int            datactrl_blocksz;
        unsigned int            datactrl_dpsm_enable;
        bool                    datactrl_first;
+       bool                    datacnt_useless;
        bool                    st_sdio;
        bool                    st_clkdiv;
        bool                    blksz_datactrl16;
-- 
2.7.4

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