mmc: sdhci-omap: re-tuning is needed after a pm transition to support emmc HS200 mode

"PM runtime functions" was been added in sdhci-omap driver in commit
f433e8a ("mmc: sdhci-omap: Implement PM runtime functions") along
with "card power off and enable aggressive PM" in commit 3edf588
("mmc: sdhci-omap: Allow SDIO card power off and enable aggressive PM").

Since then, the sdhci-omap driver doesn't work using mmc-hs200 mode
due to the tuning values being lost during a pm transition.

As for the sdhci_am654 driver, request a new tuning sequence before
suspend (sdhci_omap_runtime_suspend()), otherwise the device will
trigger cache flush error:

  mmc1: cache flush error -110 (ETIMEDOUT)
  mmc1: error -110 doing aggressive suspend

followed by I/O errors produced by fdisk -l /dev/mmcblk1boot1:

  I/O error, dev mmcblk1boot0, sector 64384 op 0x0:(READ) flags 0x80700 phys_seg 1
  prio class 2
  I/O error, dev mmcblk1boot1, sector 64384 op 0x0:(READ) flags 0x80700 phys_seg 1
  prio class 2
  I/O error, dev mmcblk1boot1, sector 64384 op 0x0:(READ) flags 0x0 phys_seg 1
  prio class 2
  Buffer I/O error on dev mmcblk1boot1, logical block 8048, async page read
  I/O error, dev mmcblk1boot0, sector 64384 op 0x0:(READ) flags 0x0 phys_seg 1
  prio class 2
  Buffer I/O error on dev mmcblk1boot0, logical block 8048, async page read

Don't re-tune if auto retuning is supported in HW (when SDHCI_TUNING_MODE_3
is available).

Link: https://lore.kernel.org/all/[email protected]
Fixes: f433e8a ("mmc: sdhci-omap: Implement PM runtime functions")
Signed-off-by: Romain Naour <[email protected]>
Reviewed-by: Tony Lindgren <[email protected]>
Acked-by: Adrian Hunter <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Ulf Hansson <[email protected]>

Author: Romain Naour

drivers/mmc/host/sdhci-omap.c

@@ -1439,6 +1439,9 @@ static int __maybe_unused sdhci_omap_runtime_suspend(struct device *dev)
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_omap_host *omap_host = sdhci_pltfm_priv(pltfm_host);
 
+	if (host->tuning_mode != SDHCI_TUNING_MODE_3)
+		mmc_retune_needed(host->mmc);
+
 	if (omap_host->con != -EINVAL)
 		sdhci_runtime_suspend_host(host);