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spi: s3c64xx: Fix large transfers with DMA

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The COUNT_VALUE in the PACKET_CNT register is 16-bit so the maximum
value is 65535.  Asking the driver to transfer a larger size currently
leads to the DMA transfer timing out.  Implement ->max_transfer_size()
and have the core split the transfer as needed.

Fixes: 230d42d422 ("spi: Add s3c64xx SPI Controller driver")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20220927112117.77599-5-vincent.whitchurch@axis.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Vincent Whitchurch 2022-09-27 13:21:17 +02:00 committed by Mark Brown
parent 8d699ff955
commit 1224e29572
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1 changed files with 9 additions and 0 deletions
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9
drivers/spi/spi-s3c64xx.c
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@ -84,6 +84,7 @@
#define S3C64XX_SPI_ST_TX_FIFORDY (1<<0)
#define S3C64XX_SPI_PACKET_CNT_EN (1<<16)
#define S3C64XX_SPI_PACKET_CNT_MASK GENMASK(15, 0)
#define S3C64XX_SPI_PND_TX_UNDERRUN_CLR (1<<4)
#define S3C64XX_SPI_PND_TX_OVERRUN_CLR (1<<3)
@ -711,6 +712,13 @@ static int s3c64xx_spi_prepare_message(struct spi_master *master,
return 0;
}
static size_t s3c64xx_spi_max_transfer_size(struct spi_device *spi)
{
struct spi_controller *ctlr = spi->controller;
return ctlr->can_dma ? S3C64XX_SPI_PACKET_CNT_MASK : SIZE_MAX;
}
static int s3c64xx_spi_transfer_one(struct spi_master *master,
struct spi_device *spi,
struct spi_transfer *xfer)
@ -1152,6 +1160,7 @@ static int s3c64xx_spi_probe(struct platform_device *pdev)
master->unprepare_transfer_hardware = s3c64xx_spi_unprepare_transfer;
master->prepare_message = s3c64xx_spi_prepare_message;
master->transfer_one = s3c64xx_spi_transfer_one;
master->max_transfer_size = s3c64xx_spi_max_transfer_size;
master->num_chipselect = sci->num_cs;
master->use_gpio_descriptors = true;
master->dma_alignment = 8;