[PATCH] spi: spi-cadence: Fix data corruption issues in slave mode

[PATCH] spi: spi-cadence: Fix data corruption issues in slave mode

[Srinivas Goud]

Remove 10us delay in cdns_spi_process_fifo() (called from cdns_spi_irq())
to fix data corruption issue on Master side when this driver
configured in Slave mode, as Slave is failed to prepare the date
on time due to above delay.

Add 10us delay before processing the RX FIFO as TX empty doesn't
guarantee valid data in RX FIFO.

Signed-off-by: Srinivas Goud <srinivas.goud@amd.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Tested-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---
 drivers/spi/spi-cadence.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index 42f101d..b21d125 100644
--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -317,12 +317,6 @@ static void cdns_spi_process_fifo(struct cdns_spi *xspi, int ntx, int nrx)
 	xspi->rx_bytes -= nrx;
 
 	while (ntx || nrx) {
-		/* When xspi in busy condition, bytes may send failed,
-		 * then spi control did't work thoroughly, add one byte delay
-		 */
-		if (cdns_spi_read(xspi, CDNS_SPI_ISR) & CDNS_SPI_IXR_TXFULL)
-			udelay(10);
-
 		if (ntx) {
 			if (xspi->txbuf)
 				cdns_spi_write(xspi, CDNS_SPI_TXD, *xspi->txbuf++);
@@ -392,6 +386,11 @@ static irqreturn_t cdns_spi_irq(int irq, void *dev_id)
 		if (xspi->tx_bytes) {
 			cdns_spi_process_fifo(xspi, trans_cnt, trans_cnt);
 		} else {
+			/* Fixed delay due to controller limitation with
+			 * RX_NEMPTY incorrect status
+			 * Xilinx AR:65885 contains more details
+			 */
+			udelay(10);
 			cdns_spi_process_fifo(xspi, 0, trans_cnt);
 			cdns_spi_write(xspi, CDNS_SPI_IDR,
 				       CDNS_SPI_IXR_DEFAULT);
@@ -439,12 +438,18 @@ static int cdns_transfer_one(struct spi_controller *ctlr,
 		cdns_spi_setup_transfer(spi, transfer);
 	} else {
 		/* Set TX empty threshold to half of FIFO depth
-		 * only if TX bytes are more than half FIFO depth.
+		 * only if TX bytes are more than FIFO depth.
 		 */
 		if (xspi->tx_bytes > xspi->tx_fifo_depth)
 			cdns_spi_write(xspi, CDNS_SPI_THLD, xspi->tx_fifo_depth >> 1);
 	}
 
+	/* When xspi in busy condition, bytes may send failed,
+	 * then spi control didn't work thoroughly, add one byte delay
+	 */
+	if (cdns_spi_read(xspi, CDNS_SPI_ISR) & CDNS_SPI_IXR_TXFULL)
+		udelay(10);
+
 	cdns_spi_process_fifo(xspi, xspi->tx_fifo_depth, 0);
 	spi_transfer_delay_exec(transfer);
 
-- 
2.1.1

Re: [PATCH] spi: spi-cadence: Fix data corruption issues in slave mode

[Mark Brown]

On Mon, 21 Aug 2023 15:00:16 +0530, Srinivas Goud wrote:
> Remove 10us delay in cdns_spi_process_fifo() (called from cdns_spi_irq())
> to fix data corruption issue on Master side when this driver
> configured in Slave mode, as Slave is failed to prepare the date
> on time due to above delay.
> 
> Add 10us delay before processing the RX FIFO as TX empty doesn't
> guarantee valid data in RX FIFO.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: spi-cadence: Fix data corruption issues in slave mode
      commit: 627d05a41ca1fbb9d390f9513af262f001f261f7

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark