linux-kernel - [PATCH 2/2] mmc: core: Add no single read retries

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Date:   Wed, 17 Feb 2021 14:22:39 +0900
From:   DooHyun Hwang <dh0421.hwang@...sung.com>
To:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, ulf.hansson@...aro.org,
        robh+dt@...nel.org, axboe@...nel.dk, adrian.hunter@...el.com,
        satyat@...gle.com, ebiggers@...gle.com, gustavoars@...nel.org
Cc:     grant.jung@...sung.com, jt77.jang@...sung.com,
        junwoo80.lee@...sung.com, jangsub.yi@...sung.com,
        sh043.lee@...sung.com, cw9316.lee@...sung.com,
        sh8267.baek@...sung.com, wkon.kim@...sung.com,
        DooHyun Hwang <dh0421.hwang@...sung.com>
Subject: [PATCH 2/2] mmc: core: Add no single read retries

This makes to handle read errors faster by not retrying
multiple block read(CMD18) errors with single block reads(CMD17).

On some bad SD Cards that have problem with read operations,
it is not helpful to retry multiple block read errors with
several single block reads, and it is delayed to treat read
operations as I/O error as much as retrying single block reads.

Signed-off-by: DooHyun Hwang <dh0421.hwang@...sung.com>
---
 drivers/mmc/core/block.c | 3 ++-
 drivers/mmc/core/host.c  | 6 ++++++
 include/linux/mmc/host.h | 3 +++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index d666e24fbe0e..e25aaf8fca34 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1809,7 +1809,8 @@ static void mmc_blk_mq_rw_recovery(struct mmc_queue *mq, struct request *req)
 
 	/* FIXME: Missing single sector read for large sector size */
 	if (!mmc_large_sector(card) && rq_data_dir(req) == READ &&
-	    brq->data.blocks > 1) {
+	    brq->data.blocks > 1 &&
+	    !card->host->no_single_read_retry) {
 		/* Read one sector at a time */
 		mmc_blk_read_single(mq, req);
 		return;
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 9b89a91b6b47..3bf5b2fc111b 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -352,6 +352,12 @@ int mmc_of_parse(struct mmc_host *host)
 	if (device_property_read_bool(dev, "no-mmc"))
 		host->caps2 |= MMC_CAP2_NO_MMC;
 
+	if (device_property_read_bool(dev, "no-single-read-retry")) {
+		dev_info(host->parent,
+			"Single block read retrying is not supported\n");
+		host->no_single_read_retry = true;
+	}
+
 	/* Must be after "non-removable" check */
 	if (device_property_read_u32(dev, "fixed-emmc-driver-type", &drv_type) == 0) {
 		if (host->caps & MMC_CAP_NONREMOVABLE)
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 26a3c7bc29ae..faec55035a63 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -502,6 +502,9 @@ struct mmc_host {
 	/* Host Software Queue support */
 	bool			hsq_enabled;
 
+	/* Do not retry multi block read as single block read */
+	bool			no_single_read_retry;
+
 	unsigned long		private[] ____cacheline_aligned;
 };
 
-- 
2.29.0