From 66dfd10173159cafa9cb0d39936b8daeaab8e3e0 Mon Sep 17 00:00:00 2001 From: James Hogan Date: Mon, 17 Nov 2014 17:49:05 +0000 Subject: [PATCH] mmc: dw_mmc: avoid write to CDTHRCTL on older versions Commit f1d2736c8156 (mmc: dw_mmc: control card read threshold) added dw_mci_ctrl_rd_thld() with an unconditional write to the CDTHRCTL register at offset 0x100. However before version 240a, the FIFO region started at 0x100, so the write messes with the FIFO and completely breaks the driver. If the version id < 240A, return early from dw_mci_ctl_rd_thld() so as not to hit this problem. Fixes: f1d2736c8156 (mmc: dw_mmc: control card read threshold) Signed-off-by: James Hogan Cc: # v3.13+ Acked-by: Jaehoon Chung Signed-off-by: Ulf Hansson --- drivers/mmc/host/dw_mmc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index b4c3044..67c0451 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -726,6 +726,13 @@ static void dw_mci_ctrl_rd_thld(struct dw_mci *host, struct mmc_data *data) WARN_ON(!(data->flags & MMC_DATA_READ)); + /* + * CDTHRCTL doesn't exist prior to 240A (in fact that register offset is + * in the FIFO region, so we really shouldn't access it). + */ + if (host->verid < DW_MMC_240A) + return; + if (host->timing != MMC_TIMING_MMC_HS200 && host->timing != MMC_TIMING_UHS_SDR104) goto disable; -- 2.7.4