linux-kernel - [PATCH] mmc: sdhci: Fix warning message when accessing RPMB in HS400 mode

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Message-Id: <20210624163045.33651-1-alcooperx@gmail.com>
Date:   Thu, 24 Jun 2021 12:30:45 -0400
From:   Al Cooper <alcooperx@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Al Cooper <alcooperx@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-mmc@...r.kernel.org, Ulf Hansson <ulf.hansson@...aro.org>
Subject: [PATCH] mmc: sdhci: Fix warning message when accessing RPMB in HS400 mode

When an eMMC device is being run in HS400 mode, any access to the
RPMB device will cause the error message "mmc1: Invalid UHS-I mode
selected". This happens as a result of tuning being disabled before
RPMB access and then re-enabled after the RPMB access is complete.
When tuning is re-enabled, the system has to switch from HS400
to HS200 to do the tuning and then back to HS400. As part of
sequence to switch from HS400 to HS200 the system is temporarily
put into HS mode. When switching to HS mode, sdhci_get_preset_value()
is called and does not have support for HS mode and prints the warning
message and returns the preset for SDR12. The fix is to add support
for MMC and SD HS modes to sdhci_get_preset_value().

This can be reproduced on any system running eMMC in HS400 mode
(not HS400ES) by using the "mmc" utility to run the following
command: "mmc rpmb read-counter /dev/mmcblk0rpmb".

Signed-off-by: Al Cooper <alcooperx@...il.com>
---
 drivers/mmc/host/sdhci.c | 4 ++++
 drivers/mmc/host/sdhci.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index bf238ade1602..6b39126fbf06 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1812,6 +1812,10 @@ static u16 sdhci_get_preset_value(struct sdhci_host *host)
 	u16 preset = 0;

 	switch (host->timing) {
+	case MMC_TIMING_MMC_HS:
+	case MMC_TIMING_SD_HS:
+		preset = sdhci_readw(host, SDHCI_PRESET_FOR_HIGH_SPEED);
+		break;
 	case MMC_TIMING_UHS_SDR12:
 		preset = sdhci_readw(host, SDHCI_PRESET_FOR_SDR12);
 		break;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 0770c036e2ff..960fed78529e 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -253,6 +253,7 @@

 /* 60-FB reserved */

+#define SDHCI_PRESET_FOR_HIGH_SPEED	0x64
 #define SDHCI_PRESET_FOR_SDR12 0x66
 #define SDHCI_PRESET_FOR_SDR25 0x68
 #define SDHCI_PRESET_FOR_SDR50 0x6A

base-commit: 7426cedc7dad67bf3c71ea6cc29ab7822e1a453f
-- 
2.17.1