mmc: meson-gx: make replace WARN_ONCE with dev_warn_once about scatterlist offset alignment

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: 79ed05e329 ("mmc: meson-gx: add support for descriptor chain mode")
Cc: stable@vger.kernel.org
Reported-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20210426175559.3110575-1-narmstrong@baylibre.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

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;
 		}
 	}