From 24835611a96e9b41ad57dd5024915106293be7e9 Mon Sep 17 00:00:00 2001 From: Heiner Kallweit Date: Sat, 10 Jun 2017 13:36:38 +0200 Subject: [PATCH] mmc: meson-gx: work around broken SDIO with certain WiFi chips There have been reports about SDIO failing with certain WiFi chips in descriptor chain mode. SD / eMMC are working fine. So let's fall back to bounce buffer mode for command SD_IO_RW_EXTENDED. This was reported to fix the error. Fixes: 79ed05e329c3 "mmc: meson-gx: add support for descriptor chain mode" Signed-off-by: Heiner Kallweit Tested-by: Martin Blumenstingl Signed-off-by: Ulf Hansson --- drivers/mmc/host/meson-gx-mmc.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c index 1842ed341af1..de962c2d5e00 100644 --- a/drivers/mmc/host/meson-gx-mmc.c +++ b/drivers/mmc/host/meson-gx-mmc.c @@ -210,6 +210,15 @@ static void meson_mmc_get_transfer_mode(struct mmc_host *mmc, int i; bool use_desc_chain_mode = true; + /* + * Broken SDIO with AP6255-based WiFi on Khadas VIM Pro has been + * reported. For some strange reason this occurs in descriptor + * chain mode only. So let's fall back to bounce buffer mode + * for command SD_IO_RW_EXTENDED. + */ + if (mrq->cmd->opcode == SD_IO_RW_EXTENDED) + return; + for_each_sg(data->sg, sg, data->sg_len, i) /* check for 8 byte alignment */ if (sg->offset & 7) {