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SubjectRe: [PATCH] Revert "spi: omap2-mcspi: Set FIFO DMA trigger level to word length"
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CC: OMAP list for good measure

On 1/13/19 2:49 PM, David Lechner wrote:
> This reverts commit b682cffa3ac6d9d9e16e9b413c45caee3b391fab.
>
> That commit breaks displays using tinydrm drivers, such as ili9225.
>
> It causes corruption in the image that is displayed (it looks like only
> 1/2 of the framebuffer data is sent, the other half of the display
> remains blank.)
>
> The following error appears multiple times:
>
> ili9225 spi1.0: EOW timed out
>
> Eventually, the system locks up without any additional errors.
>
> Cc: Vignesh R <vigneshr@ti.com>
> Signed-off-by: David Lechner <david@lechnology.com>
> ---
> drivers/spi/spi-omap2-mcspi.c | 26 +++++++++++++++++++-------
> 1 file changed, 19 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
> index 2fd8881fcd65..5a3854ff2e08 100644
> --- a/drivers/spi/spi-omap2-mcspi.c
> +++ b/drivers/spi/spi-omap2-mcspi.c
> @@ -306,7 +306,7 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi,
> struct omap2_mcspi_cs *cs = spi->controller_state;
> struct omap2_mcspi *mcspi;
> unsigned int wcnt;
> - int max_fifo_depth, bytes_per_word;
> + int max_fifo_depth, fifo_depth, bytes_per_word;
> u32 chconf, xferlevel;
>
> mcspi = spi_master_get_devdata(master);
> @@ -322,6 +322,10 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi,
> else
> max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH;
>
> + fifo_depth = gcd(t->len, max_fifo_depth);
> + if (fifo_depth < 2 || fifo_depth % bytes_per_word != 0)
> + goto disable_fifo;
> +
> wcnt = t->len / bytes_per_word;
> if (wcnt > OMAP2_MCSPI_MAX_FIFOWCNT)
> goto disable_fifo;
> @@ -329,17 +333,16 @@ static void omap2_mcspi_set_fifo(const struct spi_device *spi,
> xferlevel = wcnt << 16;
> if (t->rx_buf != NULL) {
> chconf |= OMAP2_MCSPI_CHCONF_FFER;
> - xferlevel |= (bytes_per_word - 1) << 8;
> + xferlevel |= (fifo_depth - 1) << 8;
> }
> -
> if (t->tx_buf != NULL) {
> chconf |= OMAP2_MCSPI_CHCONF_FFET;
> - xferlevel |= bytes_per_word - 1;
> + xferlevel |= fifo_depth - 1;
> }
>
> mcspi_write_reg(master, OMAP2_MCSPI_XFERLEVEL, xferlevel);
> mcspi_write_chconf0(spi, chconf);
> - mcspi->fifo_depth = max_fifo_depth;
> + mcspi->fifo_depth = fifo_depth;
>
> return;
> }
> @@ -598,6 +601,7 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
> struct dma_slave_config cfg;
> enum dma_slave_buswidth width;
> unsigned es;
> + u32 burst;
> void __iomem *chstat_reg;
> void __iomem *irqstat_reg;
> int wait_res;
> @@ -617,14 +621,22 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
> }
>
> count = xfer->len;
> + burst = 1;
> +
> + if (mcspi->fifo_depth > 0) {
> + if (count > mcspi->fifo_depth)
> + burst = mcspi->fifo_depth / es;
> + else
> + burst = count / es;
> + }
>
> memset(&cfg, 0, sizeof(cfg));
> cfg.src_addr = cs->phys + OMAP2_MCSPI_RX0;
> cfg.dst_addr = cs->phys + OMAP2_MCSPI_TX0;
> cfg.src_addr_width = width;
> cfg.dst_addr_width = width;
> - cfg.src_maxburst = es;
> - cfg.dst_maxburst = es;
> + cfg.src_maxburst = burst;
> + cfg.dst_maxburst = burst;
>
> rx = xfer->rx_buf;
> tx = xfer->tx_buf;
>

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