Thread (33 messages) 33 messages, 4 authors, 2020-05-14

RE: [PATCH v7 RESEND 07/13] spi: imx: fix ERR009165

From: Robin Gong <hidden>
Date: 2020-05-13 09:05:41
Also in: dmaengine, linux-arm-kernel, linux-spi, lkml

On 2020/05/13 Sascha Hauer [off-list ref] wrote:d
quoted hunk ↗ jump to hunk
quoted
 drivers/spi/spi-imx.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c index
f4f28a4..70df8e6 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -585,8 +585,8 @@ static int mx51_ecspi_prepare_transfer(struct
spi_imx_data *spi_imx,
quoted
 	ctrl |= mx51_ecspi_clkdiv(spi_imx, t->speed_hz, &clk);
 	spi_imx->spi_bus_clk = clk;

-	if (spi_imx->usedma)
-		ctrl |= MX51_ECSPI_CTRL_SMC;
+	/* ERR009165: work in XHC mode as PIO */
+	ctrl &= ~MX51_ECSPI_CTRL_SMC;

 	writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
@@ -617,7 +617,7 @@ static void mx51_setup_wml(struct spi_imx_data
*spi_imx)
quoted
 	 * and enable DMA request.
 	 */
 	writel(MX51_ECSPI_DMA_RX_WML(spi_imx->wml - 1) |
-		MX51_ECSPI_DMA_TX_WML(spi_imx->wml) |
+		MX51_ECSPI_DMA_TX_WML(0) |
 		MX51_ECSPI_DMA_RXT_WML(spi_imx->wml) |
 		MX51_ECSPI_DMA_TEDEN | MX51_ECSPI_DMA_RXDEN |
 		MX51_ECSPI_DMA_RXTDEN, spi_imx->base + MX51_ECSPI_DMA);
@@ -1171,7
quoted
+1171,11 @@ static int spi_imx_dma_configure(struct spi_master *master)
 	tx.direction = DMA_MEM_TO_DEV;
 	tx.dst_addr = spi_imx->base_phys + MXC_CSPITXDATA;
 	tx.dst_addr_width = buswidth;
-	tx.dst_maxburst = spi_imx->wml;
+	/*
+	 * For ERR009165 with tx_wml = 0 could enlarge burst size to fifo size
+	 * to speed up fifo filling as possible.
+	 */
+	tx.dst_maxburst = spi_imx->devtype_data->fifo_size;
In the next patch this is changed again to:

+       if (spi_imx->devtype_data->tx_glitch_fixed)
+               tx.dst_maxburst = spi_imx->wml;
+       else
+               tx.dst_maxburst = spi_imx->devtype_data->fifo_size;

So with tx_glitch_fixed we end up with tx.dst_maxburst being the same as two
patches before which is rather confusing. Better introduce tx_glitch_fixed in
this patch, or maybe even merge this patch and the next one.
Sorry confused you, I should repleace 'tx_wml=0' in the above comments with ' TX_THRESHOLD=0', which means tx transfer dma have to wait all the tx data in tx fifo transferred with ERR009165 rather than generically 'tx_wml' (for example --half fifo size used as TX_THRESHOLD). Obviously TX_THRESHOLD=0 would down performance, so enlarge dst_maxburst to fifo size as PIO with ERR009165. After ERR009165 fixed at HW level. TX_THRESHOLD could be used as common 'spi_imx->wml' so change it back. Will add more detail information in v8.
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