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authorPaul Walmsley <paul@pwsan.com>2012-08-24 06:00:18 +0000
committerChris Ball <cjb@laptop.org>2012-09-04 13:58:11 -0400
commit75b53aee2f4fe6375c6007226bf68d75b5c4a929 (patch)
treed4048b6d8a0afdabe80444a06cb2a57b607e3ee0
parent3550ccdb9d8d350e526b809bf3dd92b550a74fe1 (diff)
downloadlinux-linaro-stable-75b53aee2f4fe6375c6007226bf68d75b5c4a929.tar.gz
mmc: omap: fix broken PIO mode
After commit 26b88520b80695a6fa5fd95b5d97c03f4daf87e0 ("mmc: omap_hsmmc: remove private DMA API implementation"), the Nokia N800 here stopped booting: [ 2.086181] Waiting for root device /dev/mmcblk0p1... [ 2.324066] Unhandled fault: imprecise external abort (0x406) at 0x00000000 [ 2.331451] Internal error: : 406 [#1] ARM [ 2.335784] Modules linked in: [ 2.339050] CPU: 0 Not tainted (3.6.0-rc3 #60) [ 2.344146] PC is at default_idle+0x28/0x30 [ 2.348602] LR is at trace_hardirqs_on_caller+0x15c/0x1b0 ... This turned out to be due to memory corruption caused by long-broken PIO code in drivers/mmc/host/omap.c. (Previously, this driver had been using DMA; but the above commit caused the MMC driver to fall back to PIO mode with an unmodified Kconfig.) The PIO code, added with the rest of the driver in commit 730c9b7e6630f786fcec026fb11d2e6f2c90fdcb ("[MMC] Add OMAP MMC host driver"), confused bytes with 16-bit words. This bug caused memory located after the PIO transfer buffer to be corrupted with transfers larger than 32 bytes. The driver also did not increment the buffer pointer after the transfer occurred. This bug resulted in data corruption during any transfer larger than 64 bytes. Signed-off-by: Paul Walmsley <paul@pwsan.com> Reviewed-by: Felipe Balbi <balbi@ti.com> Tested-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Chris Ball <cjb@laptop.org>
-rw-r--r--drivers/mmc/host/omap.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
index 50e08f03aa65..a5999a74496a 100644
--- a/drivers/mmc/host/omap.c
+++ b/drivers/mmc/host/omap.c
@@ -668,7 +668,7 @@ mmc_omap_clk_timer(unsigned long data)
static void
mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
{
- int n;
+ int n, nwords;
if (host->buffer_bytes_left == 0) {
host->sg_idx++;
@@ -678,15 +678,23 @@ mmc_omap_xfer_data(struct mmc_omap_host *host, int write)
n = 64;
if (n > host->buffer_bytes_left)
n = host->buffer_bytes_left;
+
+ nwords = n / 2;
+ nwords += n & 1; /* handle odd number of bytes to transfer */
+
host->buffer_bytes_left -= n;
host->total_bytes_left -= n;
host->data->bytes_xfered += n;
if (write) {
- __raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA), host->buffer, n);
+ __raw_writesw(host->virt_base + OMAP_MMC_REG(host, DATA),
+ host->buffer, nwords);
} else {
- __raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA), host->buffer, n);
+ __raw_readsw(host->virt_base + OMAP_MMC_REG(host, DATA),
+ host->buffer, nwords);
}
+
+ host->buffer += nwords;
}
static inline void mmc_omap_report_irq(u16 status)