From c70805dca13970d18a4a9960bdc1d2f10de59057 Mon Sep 17 00:00:00 2001 From: Martin Blumenstingl Date: Mon, 18 May 2020 00:29:06 +0200 Subject: mmc: meson-mx-sdhc: Fix manual RX FIFO flushing For Meson8 and Meson8b SoCs the vendor driver follows the following pattern: - for eMMC and SD cards in .set_pdma it sets: pdma->rxfifo_manual_flush = 1; - for SDIO cards in .set_pdma it sets: pdma->rxfifo_manual_flush = 0; - before syncing the DMA read buffer is sets: pdma->rxfifo_manual_flush |= 0x02; Set the second bit of MESON_SDHC_PDMA_RXFIFO_MANUAL_FLUSH without clearing the first bit before syncing the DMA read buffer. This fixes a problem where Meson8 and Meson8b SoCs would read random garbage from SD cards. It is not clear why it worked for eMMC cards. This manifested in the following errors when plugging in an SD card: unrecognised SCR structure version Cc: Thomas Graichen Signed-off-by: Martin Blumenstingl Link: https://lore.kernel.org/r/20200517222907.1277787-1-martin.blumenstingl@googlemail.com Signed-off-by: Ulf Hansson --- drivers/mmc/host/meson-mx-sdhc-mmc.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'drivers/mmc') diff --git a/drivers/mmc/host/meson-mx-sdhc-mmc.c b/drivers/mmc/host/meson-mx-sdhc-mmc.c index 5c00958d7754..53e3f6a4245a 100644 --- a/drivers/mmc/host/meson-mx-sdhc-mmc.c +++ b/drivers/mmc/host/meson-mx-sdhc-mmc.c @@ -586,10 +586,17 @@ static irqreturn_t meson_mx_sdhc_irq_thread(int irq, void *irq_data) cmd->data->flags & MMC_DATA_READ) { meson_mx_sdhc_wait_cmd_ready(host->mmc); + /* + * If MESON_SDHC_PDMA_RXFIFO_MANUAL_FLUSH was + * previously 0x1 then it has to be set to 0x3. If it + * was 0x0 before then it has to be set to 0x2. Without + * this reading SD cards sometimes transfers garbage, + * which results in cards not being detected due to: + * unrecognised SCR structure version + */ val = FIELD_PREP(MESON_SDHC_PDMA_RXFIFO_MANUAL_FLUSH, 2); - regmap_update_bits(host->regmap, MESON_SDHC_PDMA, - MESON_SDHC_PDMA_RXFIFO_MANUAL_FLUSH, + regmap_update_bits(host->regmap, MESON_SDHC_PDMA, val, val); } -- cgit v1.2.3-70-g09d2