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From:   Neil Armstrong <narmstrong@baylibre.com>
To:     ulf.hansson@linaro.org, khilman@baylibre.com
Cc:     linux-mmc@vger.kernel.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Neil Armstrong <narmstrong@baylibre.com>,
        Christian Hewitt <christianshewitt@gmail.com>
Subject: [PATCH 1/2] mmc: meson-gx: make replace WARN_ONCE with dev_warn_once about scatterlist offset alignment
Date:   Mon, 26 Apr 2021 19:55:58 +0200
Message-Id: <20210426175559.3110575-1-narmstrong@baylibre.com>
MIME-Version: 1.0
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Some drivers like ath10k can sometimg give an sg buffer with an offset whose alignment
is not compatible with the Amlogic DMA descriptor engine requirements.

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

This should be ultimately fixed in ath10k, but since it's only a performance issue
the warning should be removed.

Fixes: 79ed05e329c3 ("mmc: meson-gx: add support for descriptor chain mode")
Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/mmc/host/meson-gx-mmc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index b8b771b643cc..1c61f0f24c09 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -258,7 +258,9 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc,
 	for_each_sg(data->sg, sg, data->sg_len, i) {
 		/* check for 8 byte alignment */
 		if (sg->offset % 8) {
-			WARN_ONCE(1, "unaligned scatterlist buffer\n");
+			dev_warn_once(mmc_dev(mmc),
+				      "unaligned sg offset %u, disabling descriptor DMA for transfer\n",
+				      sg->offset);
 			return;
 		}
 	}
-- 
2.25.1