linux-kernel - [PATCH 5/5] mmc: core: Add support for graceful host removal for SD

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Message-ID: <20250320140040.162416-6-ulf.hansson@linaro.org>
Date: Thu, 20 Mar 2025 15:00:36 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: linux-mmc@...r.kernel.org,
	Ulf Hansson <ulf.hansson@...aro.org>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
	Wolfram Sang <wsa+renesas@...g-engineering.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 5/5] mmc: core: Add support for graceful host removal for SD

An mmc host driver may allow to unbind from its corresponding host device.
If an SD card is attached to the host, the mmc core will just try to cut
the power for it, without obeying to the SD spec that potentially may
damage the card.

Let's fix this problem by implementing a graceful power-down of the card at
host removal.

Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
---
 drivers/mmc/core/sd.c | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 8eba697d3d86..cb4254a43f85 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1596,15 +1596,6 @@ static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
 	return err;
 }
 
-/*
- * Host is being removed. Free up the current card.
- */
-static void mmc_sd_remove(struct mmc_host *host)
-{
-	mmc_remove_card(host->card);
-	host->card = NULL;
-}
-
 /*
  * Card detection - card is alive.
  */
@@ -1630,7 +1621,8 @@ static void mmc_sd_detect(struct mmc_host *host)
 	mmc_put_card(host->card, NULL);
 
 	if (err) {
-		mmc_sd_remove(host);
+		mmc_remove_card(host->card);
+		host->card = NULL;
 
 		mmc_claim_host(host);
 		mmc_detach_bus(host);
@@ -1730,6 +1722,19 @@ static int _mmc_sd_suspend(struct mmc_host *host)
 	return err;
 }
 
+/*
+ * Host is being removed. Free up the current card and do a graceful power-off.
+ */
+static void mmc_sd_remove(struct mmc_host *host)
+{
+	get_device(&host->card->dev);
+	mmc_remove_card(host->card);
+
+	_mmc_sd_suspend(host);
+
+	put_device(&host->card->dev);
+	host->card = NULL;
+}
 /*
  * Callback for suspend
  */
-- 
2.43.0