linux-kernel - [PATCH 2/3] mmc: sdhci: add quirk to prevent higher speed modes

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Message-Id: <20180628081331.13051-3-stefan@agner.ch>
Date:   Thu, 28 Jun 2018 10:13:30 +0200
From:   Stefan Agner <stefan@...er.ch>
To:     adrian.hunter@...el.com, ulf.hansson@...aro.org
Cc:     fabio.estevam@....com, haibo.chen@....com, aisheng.dong@....com,
        michael@...rulasolutions.com, rmk+kernel@...linux.org.uk,
        linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stefan Agner <stefan@...er.ch>
Subject: [PATCH 2/3] mmc: sdhci: add quirk to prevent higher speed modes

Some hosts are capable of running higher speed modes but do not
have the board support for it. Introduce a quirk which prevents
the stack from using modes running at 100MHz or faster.

Signed-off-by: Stefan Agner <stefan@...er.ch>
---
 drivers/mmc/host/sdhci.c | 8 ++++++++
 drivers/mmc/host/sdhci.h | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 1c828e0e9905..8ac257dfaab3 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -3749,6 +3749,14 @@ int sdhci_setup_host(struct sdhci_host *host)
 		}
 	}
 
+	if (host->quirks2 & SDHCI_QUIRK2_NO_UHS_HS200_HS400) {
+		host->caps1 &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
+				 SDHCI_SUPPORT_DDR50);
+
+		mmc->caps2 &= ~(MMC_CAP2_HSX00_1_8V | MMC_CAP2_HSX00_1_2V |
+				MMC_CAP2_HS400_ES);
+	}
+
 	if (host->quirks2 & SDHCI_QUIRK2_NO_1_8_V) {
 		host->caps1 &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_SUPPORT_SDR50 |
 				 SDHCI_SUPPORT_DDR50);
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 23966f887da6..cb2433d6d61f 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -450,6 +450,8 @@ struct sdhci_host {
  * obtainable timeout.
  */
 #define SDHCI_QUIRK2_DISABLE_HW_TIMEOUT			(1<<17)
+/* Do not support any higher speeds (>50MHz) */
+#define SDHCI_QUIRK2_NO_UHS_HS200_HS400			(1<<18)
 
 	int irq;		/* Device IRQ */
 	void __iomem *ioaddr;	/* Mapped address */
-- 
2.18.0