The patch titled
atmel_spi: minor updates
has been added to the -mm tree. Its filename is
atmel_spi-minor-updates.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: atmel_spi: minor updates
From: David Brownell <david-b@xxxxxxxxxxx>
Minor updates to atmel_spi:
- DMA:
* Comments to explain the DMA policies
* Report any mapping errors from spi_transfer()
* Remove extra loop for DMA mapping
- Diagnostics: report minimum clock rate, if we need to reject a
spi_setup() request because that rate is too low.
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Cc: Haavard Skinnemoen <hskinnemoen@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/spi/atmel_spi.c | 57 ++++++++++++++++++++++++++++++--------
1 file changed, 45 insertions(+), 12 deletions(-)
diff -puN drivers/spi/atmel_spi.c~atmel_spi-minor-updates drivers/spi/atmel_spi.c
--- a/drivers/spi/atmel_spi.c~atmel_spi-minor-updates
+++ a/drivers/spi/atmel_spi.c
@@ -184,18 +184,39 @@ static void atmel_spi_next_message(struc
atmel_spi_next_xfer(master, msg);
}
-static void
+/*
+ * For DMA, tx_buf/tx_dma have the same relationship as rx_buf/rx_dma:
+ * - The buffer is either valid for CPU access, else NULL
+ * - If the buffer is valid, so is its DMA addresss
+ *
+ * This driver manages the dma addresss unless message->is_dma_mapped.
+ */
+static int
atmel_spi_dma_map_xfer(struct atmel_spi *as, struct spi_transfer *xfer)
{
+ struct device *dev = &as->pdev->dev;
+
xfer->tx_dma = xfer->rx_dma = INVALID_DMA_ADDRESS;
- if (xfer->tx_buf)
- xfer->tx_dma = dma_map_single(&as->pdev->dev,
+ if (xfer->tx_buf) {
+ xfer->tx_dma = dma_map_single(dev,
(void *) xfer->tx_buf, xfer->len,
DMA_TO_DEVICE);
- if (xfer->rx_buf)
- xfer->rx_dma = dma_map_single(&as->pdev->dev,
+ if (dma_mapping_error(xfer->tx_dma))
+ return -ENOMEM;
+ }
+ if (xfer->rx_buf) {
+ xfer->rx_dma = dma_map_single(dev,
xfer->rx_buf, xfer->len,
DMA_FROM_DEVICE);
+ if (dma_mapping_error(xfer->tx_dma)) {
+ if (xfer->tx_buf)
+ dma_unmap_single(dev,
+ xfer->tx_dma, xfer->len,
+ DMA_TO_DEVICE);
+ return -ENOMEM;
+ }
+ }
+ return 0;
}
static void atmel_spi_dma_unmap_xfer(struct spi_master *master,
@@ -398,8 +419,9 @@ static int atmel_spi_setup(struct spi_de
scbr = ((bus_hz + spi->max_speed_hz - 1)
/ spi->max_speed_hz);
if (scbr >= (1 << SPI_SCBR_SIZE)) {
- dev_dbg(&spi->dev, "setup: %d Hz too slow, scbr %u\n",
- spi->max_speed_hz, scbr);
+ dev_dbg(&spi->dev,
+ "setup: %d Hz too slow, scbr %u; min %ld Hz\n",
+ spi->max_speed_hz, scbr, bus_hz/255);
return -EINVAL;
}
} else
@@ -465,12 +487,19 @@ static int atmel_spi_transfer(struct spi
dev_dbg(&spi->dev, "no protocol options yet\n");
return -ENOPROTOOPT;
}
- }
- /* scrub dcache "early" */
- if (!msg->is_dma_mapped) {
- list_for_each_entry(xfer, &msg->transfers, transfer_list)
- atmel_spi_dma_map_xfer(as, xfer);
+ /*
+ * DMA map early, for performance (empties dcache ASAP) and
+ * better fault reporting. This is a DMA-only driver.
+ *
+ * NOTE that if dma_unmap_single() ever starts to do work on
+ * platforms supported by this driver, we would need to clean
+ * up mappings for previously-mapped transfers.
+ */
+ if (!msg->is_dma_mapped) {
+ if (atmel_spi_dma_map_xfer(as, xfer) < 0)
+ return -ENOMEM;
+ }
}
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
@@ -537,6 +566,10 @@ static int __init atmel_spi_probe(struct
as = spi_master_get_devdata(master);
+ /*
+ * Scratch buffer is used for throwaway rx and tx data.
+ * It's coherent to minimize dcache pollution.
+ */
as->buffer = dma_alloc_coherent(&pdev->dev, BUFFER_SIZE,
&as->buffer_dma, GFP_KERNEL);
if (!as->buffer)
_
Patches currently in -mm which might be from david-b@xxxxxxxxxxx are
git-avr32.patch
git-leds.patch
git-mmc.patch
git-backlight.patch
char-genrtc-use-wait_event_interruptible.patch
spi-controller-drivers-check-for-unsupported-modes.patch
spi-controller-drivers-check-for-unsupported-modes-update.patch
spi-add-3wire-mode-flag.patch
spi-add-3wire-mode-flag-fix.patch
spidev-compiler-warning-gone.patch
spi_lm70llp-parport-adapter-driver-correction.patch
spi_mpc83xxc-underclocking-hotfix.patch
atmel_spi-minor-updates.patch
rtc-ds1307-cleanups.patch
rtc-rs5c372-becomes-a-new-style-i2c-driver.patch
thecus-n2100-register-rtc-rs5c372-i2c-device.patch
-
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