mmc: dw_mmc: check fifo status with a timeout in fifo

A patch from »rockchip: allow rk3188 to boot from mmc devices« in state Mailinglist for u-boot

From: Heiko Stuebner <heiko@...> Date: Thu, 20 Sep 2018 13:08:23 +0200

Commit-Message

While trying to enable the dw_mmc on rk3188 I managed to confuse and hang the dw_mmc controller into not delivering further data. The fifo state never became ready and the driver was iterating in the while loop reading 0-byte packets forever. So inspired by how other implementations handle this, check the fifo- state beforhand and add a timeout to catch any glaring fifo issues without hanging uboot altogether. Signed-off-by: Heiko Stuebner <heiko@...>

Patch-Comment

drivers/mmc/dw_mmc.c | 32 ++++++++++++++++++++++++++++++-- include/dwmmc.h | 2 ++ 2 files changed, 32 insertions(+), 2 deletions(-)

Statistics

  • 32 lines added
  • 2 lines removed

Changes

----------------------------- drivers/mmc/dw_mmc.c -----------------------------
index 13180fc0d6..3c702b3ed8 100644
@@ -92,6 +92,24 @@ static void dwmci_prepare_data(struct dwmci_host *host,
dwmci_writel(host, DWMCI_BYTCNT, data->blocksize * data->blocks);
}
+static int dwmci_fifo_ready(struct dwmci_host *host, u32 bit, u32 *len)
+{
+ u32 timeout = 20000;
+
+ *len = dwmci_readl(host, DWMCI_STATUS);
+ while (--timeout && (*len & bit)) {
+ udelay(200);
+ *len = dwmci_readl(host, DWMCI_STATUS);
+ }
+
+ if (!timeout) {
+ debug("%s: FIFO underflow timeout\n", __func__);
+ return -ETIMEDOUT;
+ }
+
+ return 0;
+}
+
static int dwmci_data_transfer(struct dwmci_host *host, struct mmc_data *data)
{
int ret = 0;
@@ -122,7 +140,12 @@ static int dwmci_data_transfer(struct dwmci_host *host, struct mmc_data *data)
if (data->flags == MMC_DATA_READ &&
(mask & DWMCI_INTMSK_RXDR)) {
while (size) {
- len = dwmci_readl(host, DWMCI_STATUS);
+ ret = dwmci_fifo_ready(host,
+ DWMCI_FIFO_EMPTY,
+ &len);
+ if (ret < 0)
+ break;
+
len = (len >> DWMCI_FIFO_SHIFT) &
DWMCI_FIFO_MASK;
len = min(size, len);
@@ -136,7 +159,12 @@ static int dwmci_data_transfer(struct dwmci_host *host, struct mmc_data *data)
} else if (data->flags == MMC_DATA_WRITE &&
(mask & DWMCI_INTMSK_TXDR)) {
while (size) {
- len = dwmci_readl(host, DWMCI_STATUS);
+ ret = dwmci_fifo_ready(host,
+ DWMCI_FIFO_FULL,
+ &len);
+ if (ret < 0)
+ break;
+
len = fifo_depth - ((len >>
DWMCI_FIFO_SHIFT) &
DWMCI_FIFO_MASK);
------------------------------- include/dwmmc.h --------------------------------
index bc1d6e3abb..0f9d51b557 100644
@@ -103,6 +103,8 @@
#define DWMCI_CTYPE_8BIT (1 << 16)
/* Status Register */
+#define DWMCI_FIFO_EMPTY (1 << 2)
+#define DWMCI_FIFO_FULL (1 << 3)
#define DWMCI_BUSY (1 << 9)
#define DWMCI_FIFO_MASK 0x1fff
#define DWMCI_FIFO_SHIFT 17
 
 

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