[PATCH v2 3/4] mmc: sdhci_am654: Clear ITAPDLY on tuning failure

["Diogo Ivo (Schneider Electric)" <diogo.ivo@bootlin.com>]

When tuning fails, stale ITAPDLY values can persist and interfere with
subsequent I/O accesses, for example in DDR50 mode in cards with no tuning
support. Move the ITAPDLY enable setting out of the tuning loop to after
successful tuning, and explicitly clear ITAPDLY (delay and enable) when
tuning fails so that we are sure only working values are actually left in
hardware.

Fixes: 901d16e46296 ("mmc: sdhci_am654: Add retry tuning")
Cc: <stable@vger.kernel.org>
Signed-off-by: Diogo Ivo (Schneider Electric) <diogo.ivo@bootlin.com>
---
Changes in v2:
 - As suggested by Sashiko clear the values in itap_del_sel[] and itap_del_ena[]
   so that they agree with what is written in HW and subsequent runtime_suspend()
   and runtime_resume() can never write stale values.
 - Remove now unused timing variable
---
 drivers/mmc/host/sdhci_am654.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 0db587e702ac..8ce10422bba0 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -527,7 +527,6 @@ static int sdhci_am654_do_tuning(struct sdhci_host *host,
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
-	unsigned char timing = host->mmc->ios.timing;
 	struct window fail_window[ITAPDLY_LENGTH];
 	struct device *dev = mmc_dev(host->mmc);
 	u8 curr_pass, itap;
@@ -536,11 +535,8 @@ static int sdhci_am654_do_tuning(struct sdhci_host *host,
 
 	memset(fail_window, 0, sizeof(fail_window));
 
-	/* Enable ITAPDLY */
-	sdhci_am654->itap_del_ena[timing] = 0x1;
-
 	for (itap = 0; itap < ITAPDLY_LENGTH; itap++) {
-		sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
+		sdhci_am654_write_itapdly(sdhci_am654, itap, 0x1);
 
 		curr_pass = !mmc_send_tuning(host->mmc, opcode, NULL);
 
@@ -584,10 +580,16 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
 
 	if (itapdly < 0) {
 		dev_err(dev, "Failed to find itapdly, fail tuning\n");
+		sdhci_am654_write_itapdly(sdhci_am654, 0, 0);
+		sdhci_am654->itap_del_ena[timing] = 0;
+		sdhci_am654->itap_del_sel[timing] = 0;
 		return -1;
 	}
 
 	dev_dbg(dev, "Passed tuning, final itapdly=%d\n", itapdly);
+
+	/* Enable ITAPDLY */
+	sdhci_am654->itap_del_ena[timing] = 0x1;
 	sdhci_am654_write_itapdly(sdhci_am654, itapdly, sdhci_am654->itap_del_ena[timing]);
 	/* Save ITAPDLY */
 	sdhci_am654->itap_del_sel[timing] = itapdly;

-- 
2.55.0