From: Vincent Whitchurch <vincent.whitchurch@axis.com>
To: <broonie@kernel.org>, <krzysztof.kozlowski@linaro.org>,
<andi@etezian.org>
Cc: <kernel@axis.com>,
Vincent Whitchurch <vincent.whitchurch@axis.com>,
<alim.akhtar@samsung.com>, <linux-spi@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
<linux-samsung-soc@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>
Subject: [PATCH 4/4] spi: s3c64xx: Fix large transfers with DMA
Date: Fri, 16 Sep 2022 13:39:51 +0200 [thread overview]
Message-ID: <20220916113951.228398-5-vincent.whitchurch@axis.com> (raw)
In-Reply-To: <20220916113951.228398-1-vincent.whitchurch@axis.com>
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. Fix this by splitting the
transfer as needed.
With this, the len>64 KiB tests in spi-loopback-test pass.
(Note that len==64 KiB tests work even without this patch for some reason.
The driver programs 0 to the COUNT_VALUE field in that case, but it's
unclear if it's by design, since the hardware documentation doesn't say
anything about the behaviour when COUNT_VALUE == 0, so play it safe and
split at 65535.)
Fixes: 230d42d422e7b69 ("spi: Add s3c64xx SPI Controller driver")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---
drivers/spi/spi-s3c64xx.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 7f346866614a..85e1d1f90109 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -701,6 +701,16 @@ static int s3c64xx_spi_prepare_message(struct spi_master *master,
struct spi_device *spi = msg->spi;
struct s3c64xx_spi_csinfo *cs = spi->controller_data;
+ if (master->can_dma) {
+ int ret;
+
+ /* Limited by size of PACKET_CNT.COUNT_VALUE. */
+ ret = spi_split_transfers_maxsize(master, msg, 65535,
+ GFP_KERNEL | GFP_DMA);
+ if (ret)
+ return ret;
+ }
+
/* Configure feedback delay */
if (!cs)
/* No delay if not defined */
--
2.34.1
next prev parent reply other threads:[~2022-09-16 11:40 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 11:39 [PATCH 0/4] spi: Fix DMA bugs in (not only) spi-s3c64xx Vincent Whitchurch
2022-09-16 11:39 ` [PATCH 1/4] spi: spi-loopback-test: Add test to trigger DMA/PIO mixing Vincent Whitchurch
2022-09-19 14:41 ` Mark Brown
2022-09-16 11:39 ` [PATCH 2/4] spi: Save current RX and TX DMA devices Vincent Whitchurch
2022-09-16 11:39 ` [PATCH 3/4] spi: Fix cache corruption due to DMA/PIO overlap Vincent Whitchurch
2022-09-16 16:06 ` kernel test robot
2022-09-16 11:39 ` Vincent Whitchurch [this message]
2022-09-19 9:43 ` [PATCH 4/4] spi: s3c64xx: Fix large transfers with DMA Krzysztof Kozlowski
2022-09-19 14:38 ` Mark Brown
2022-09-26 13:42 ` Vincent Whitchurch
2022-09-26 13:52 ` Mark Brown
2022-09-19 16:50 ` (subset) [PATCH 0/4] spi: Fix DMA bugs in (not only) spi-s3c64xx Mark Brown
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