From: David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
To: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
Andrea Paterniani
<a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org>
Subject: [patch 2.6.28-rc5] spi_imx: full duplex dma corruption bugfix
Date: Tue, 18 Nov 2008 14:06:24 -0800 [thread overview]
Message-ID: <200811181406.25041.david-b@pacbell.net> (raw)
From: Andrea Paterniani <a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org>
Fix unsafe order in dma mapping operation: always flush data from
the cache *BEFORE* invalidating it, to allow full duplex transfers
where the same buffer may be used for both writes and reads.
Signed-off-by: Andrea Paterniani <a.paterniani-03BXCEkGbFHYGGNLXY5/rw@public.gmane.org>
Signed-off-by: David Brownell <dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
---
drivers/spi/spi_imx.c | 45 ++++++++++++++++++++++-----------------------
1 file changed, 22 insertions(+), 23 deletions(-)
--- a/drivers/spi/spi_imx.c
+++ b/drivers/spi/spi_imx.c
@@ -506,20 +506,6 @@ static int map_dma_buffers(struct driver
if (!IS_DMA_ALIGNED(drv_data->rx) || !IS_DMA_ALIGNED(drv_data->tx))
return -1;
- /* NULL rx means write-only transfer and no map needed
- since rx DMA will not be used */
- if (drv_data->rx) {
- buf = drv_data->rx;
- drv_data->rx_dma = dma_map_single(
- dev,
- buf,
- drv_data->len,
- DMA_FROM_DEVICE);
- if (dma_mapping_error(dev, drv_data->rx_dma))
- return -1;
- drv_data->rx_dma_needs_unmap = 1;
- }
-
if (drv_data->tx == NULL) {
/* Read only message --> use drv_data->dummy_dma_buf for dummy
writes to achive reads */
@@ -533,18 +519,31 @@ static int map_dma_buffers(struct driver
buf,
drv_data->tx_map_len,
DMA_TO_DEVICE);
- if (dma_mapping_error(dev, drv_data->tx_dma)) {
- if (drv_data->rx_dma) {
- dma_unmap_single(dev,
- drv_data->rx_dma,
- drv_data->len,
- DMA_FROM_DEVICE);
- drv_data->rx_dma_needs_unmap = 0;
- }
+ if (dma_mapping_error(dev, drv_data->tx_dma))
return -1;
- }
drv_data->tx_dma_needs_unmap = 1;
+ /* NULL rx means write-only transfer and no map needed
+ * since rx DMA will not be used */
+ if (drv_data->rx) {
+ buf = drv_data->rx;
+ drv_data->rx_dma = dma_map_single(dev,
+ buf,
+ drv_data->len,
+ DMA_FROM_DEVICE);
+ if (dma_mapping_error(dev, drv_data->rx_dma)) {
+ if (drv_data->tx_dma) {
+ dma_unmap_single(dev,
+ drv_data->tx_dma,
+ drv_data->tx_map_len,
+ DMA_TO_DEVICE);
+ drv_data->tx_dma_needs_unmap = 0;
+ }
+ return -1;
+ }
+ drv_data->rx_dma_needs_unmap = 1;
+ }
+
return 0;
}
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next reply other threads:[~2008-11-18 22:06 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-18 22:06 David Brownell [this message]
[not found] ` <200811181406.25041.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-11-21 8:13 ` au1550-spi: full duplex dma data corruption bugfix Jan Nikitenko
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