linux-kernel - [PATCH v2] mmc: meson-gx: replace WARN_ONCE with dev_warn_once about scatterlist size alignment in block mode

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Date:   Fri, 16 Apr 2021 11:43:47 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        lebed.dmitry@...il.com, Neil Armstrong <narmstrong@...libre.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: [PATCH v2] mmc: meson-gx: replace WARN_ONCE with dev_warn_once about scatterlist size alignment in block mode

Since commit e085b51c74cc ("mmc: meson-gx: check for scatterlist size alignment in block mode"),
support for SDIO SD_IO_RW_EXTENDED transferts are properly filtered but some driver
like brcmfmac still gives a block sg buffer size not aligned with SDIO block,
triggerring a WARN_ONCE() with scary stacktrace even if the transfer works fine
but with possible degraded performances.

Simply replace with dev_warn_once() to inform user this should be fixed to avoid
degraded performance.

This should be ultimately fixed in brcmfmac, but since it's only a performance issue
the warning should be removed.

Fixes: e085b51c74cc ("mmc: meson-gx: check for scatterlist size alignment in block mode")
Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
---
Changes since v1:
- replace WARN_ONCE with dev_warn_once and explicit the warning message

 drivers/mmc/host/meson-gx-mmc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index eb6c02bc4a02..b8b771b643cc 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -247,8 +247,9 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
 		 */
 		for_each_sg(data->sg, sg, data->sg_len, i) {
 			if (sg->length % data->blksz) {
-				WARN_ONCE(1, "unaligned sg len %u blksize %u\n",
-					  sg->length, data->blksz);
+				dev_warn_once(mmc_dev(mmc),
+					      "unaligned sg len %u blksize %u, disabling descriptor DMA for transfer\n",
+					      sg->length, data->blksz);
 				return;
 			}
 		}
-- 
2.25.1