[PATCH 1/2] mmc: sdhci_am654: Add retry tuning

Judith Mendez
2024-08-15T20:15:45Z

Add retry tuning up to 10 times if we fail to find
a failing region or no passing itapdly. This is
necessary since some eMMC's have been observed to never
find a failing itapdly on the first couple of tuning
iterations, but eventually do. It been observed that the
tuning algorithm does not need to loop more than 10 times
before finding a failing itapdly.

Signed-off-by: Judith Mendez <jm@ti.com>
---
drivers/mmc/host/sdhci_am654.c | 30 +++++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 64e10f7c9faa3..c3d485bd4d553 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -86,6 +86,7 @@

#define CLOCK_TOO_SLOW_HZ 50000000
#define SDHCI_AM654_AUTOSUSPEND_DELAY -1
+#define RETRY_TUNING_MAX 10

/* Command Queue Host Controller Interface Base address */
#define SDHCI_AM654_CQE_BASE_ADDR 0x200
@@ -151,6 +152,7 @@ struct sdhci_am654_data {
u32 flags;
u32 quirks;
bool dll_enable;
+ u32 tuning_loop;

#define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
};
@@ -453,12 +455,14 @@ static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
int prev_fail_end = -1;
u8 i;

- if (!num_fails)
- return ITAPDLY_LAST_INDEX >> 1;
+ if (!num_fails) {
+ /* Retry tuning */
+ return -1;
+ }

if (fail_window->length == ITAPDLY_LENGTH) {
- dev_err(dev, "No passing ITAPDLY, return 0\n");
- return 0;
+ /* Retry tuning */
+ return -1;
}

first_fail_start = fail_window->start;
@@ -504,6 +508,7 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
u8 curr_pass, itap;
u8 fail_index = 0;
u8 prev_pass = 1;
+ int ret;

memset(fail_window, 0, sizeof(fail_window));

@@ -532,10 +537,20 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
if (fail_window[fail_index].length != 0)
fail_index++;

- itap = sdhci_am654_calculate_itap(host, fail_window, fail_index,
- sdhci_am654->dll_enable);
+ ret = sdhci_am654_calculate_itap(host, fail_window, fail_index,
+ sdhci_am654->dll_enable);

- sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
+ if (ret >= 0) {
+ itap = ret;
+ sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
+ } else {
+ if (sdhci_am654->tuning_loop < RETRY_TUNING_MAX) {
+ sdhci_am654->tuning_loop++;
+ sdhci_am654_platform_execute_tuning(host, opcode);
+ } else {
+ return -1;
+ }
+ }

/* Save ITAPDLY */
sdhci_am654->itap_del_sel[timing] = itap;
@@ -908,6 +923,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
goto err_pltfm_free;
}

+ sdhci_am654->tuning_loop = 0;
host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;

pm_runtime_get_noresume(dev);
--
2.46.0