From e385ea63f44b475e034a78b6d8bc6bb50caf72ca Mon Sep 17 00:00:00 2001
From: David Brownell <dbrownell@users.sourceforge.net>
Date: Tue, 2 Sep 2008 14:35:46 -0700
Subject: [PATCH] mmc: at91_mci: don't use coherent dma buffers
At91_mci is abusing dma_free_coherent(), which may not be called with IRQs
disabled. I saw "mkfs.ext3" on an MMC card objecting voluminously as each
write completed:
WARNING: at arch/arm/mm/consistent.c:368 dma_free_coherent+0x2c/0x224()
[<c002726c>] (dump_stack+0x0/0x14) from [<c00387d4>] (warn_on_slowpath+0x4c/0x68)
[<c0038788>] (warn_on_slowpath+0x0/0x68) from [<c0028768>] (dma_free_coherent+0x2c/0x224)
r6:00008008 r5:ffc06000 r4:00000000
[<c002873c>] (dma_free_coherent+0x0/0x224) from [<c01918ac>] (at91_mci_irq+0x374/0x420)
[<c0191538>] (at91_mci_irq+0x0/0x420) from [<c0065d9c>] (handle_IRQ_event+0x2c/0x6c)
...
This bug has been around for a LONG time. The MM warning is from late
2005, but the driver merged a year later ... so I'm puzzled why nobody
noticed this before now.
The fix involves noting that this buffer shouldn't be DMA-coherent; it's
just used for normal DMA writes. So replace it with standard kmalloc()
buffering and DMA mapping calls.
This is the quickie fix. A better one would not rely on allocating large
bounce buffers. (Note that dma_alloc_coherent could have failed too, but
that case was ignored... kmalloc is a bit more likely to fail though.)
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Pierre Ossman <drzeus-mmc@drzeus.cx>
Cc: Andrew Victor <linux@maxim.org.za>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
drivers/mmc/host/at91_mci.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/mmc/host/at91_mci.c b/drivers/mmc/host/at91_mci.c
index 6915f40ac8ab4..1f8b5b36222c2 100644
--- a/drivers/mmc/host/at91_mci.c
+++ b/drivers/mmc/host/at91_mci.c
@@ -621,12 +621,21 @@ static void at91_mci_send_command(struct at91mci_host *host, struct mmc_command
if (cpu_is_at91sam9260 () || cpu_is_at91sam9263())
if (host->total_length < 12)
host->total_length = 12;
- host->buffer = dma_alloc_coherent(NULL,
- host->total_length,
- &host->physical_address, GFP_KERNEL);
+
+ host->buffer = kmalloc(host->total_length, GFP_KERNEL);
+ if (!host->buffer) {
+ pr_debug("Can't alloc tx buffer\n");
+ cmd->error = -ENOMEM;
+ mmc_request_done(host->mmc, host->request);
+ return;
+ }
at91_mci_sg_to_dma(host, data);
+ host->physical_address = dma_map_single(NULL,
+ host->buffer, host->total_length,
+ DMA_TO_DEVICE);
+
pr_debug("Transmitting %d bytes\n", host->total_length);
at91_mci_write(host, ATMEL_PDC_TPR, host->physical_address);
@@ -694,7 +703,10 @@ static void at91_mci_completed_command(struct at91mci_host *host, unsigned int s
cmd->resp[3] = at91_mci_read(host, AT91_MCI_RSPR(3));
if (host->buffer) {
- dma_free_coherent(NULL, host->total_length, host->buffer, host->physical_address);
+ dma_unmap_single(NULL,
+ host->physical_address, host->total_length,
+ DMA_TO_DEVICE);
+ kfree(host->buffer);
host->buffer = NULL;
}
--
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