Am Sonntag, den 27.01.2019, 23:08 -0700 schrieb Angus Ainslie (Purism):
> On i.mx8 mscale B0 chip, AHB/SDMA clock ratio 2:1 can't be supportted,
> since SDMA clock ratio has to be increased to 250Mhz, AHB can't reach
> to 500Mhz, so use 1:1 instead.
>
> Based on NXP commit MLK-16841-1 by Robin Gong <yibin.g...@nxp.com>
>
> Signed-off-by: Angus Ainslie (Purism) <an...@akkea.ca>
Reviewed-by: Lucas Stach <l.st...@pengutronix.de>
> ---
> drivers/dma/imx-sdma.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index 0b3a67ff8e82..757fad2fbfae 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -440,6 +440,8 @@ struct sdma_engine {
> unsigned int irq;
> dma_addr_t bd0_phys;
> struct sdma_buffer_descriptor *bd0;
> + /* clock ratio for AHB:SDMA core. 1:1 is 1, 2:1 is 0*/
> + bool clk_ratio;
> };
>
> static int sdma_config_write(struct dma_chan *chan,
> @@ -662,8 +664,11 @@ static int sdma_run_channel0(struct sdma_engine *sdma)
> dev_err(sdma->dev, "Timeout waiting for CH0 ready\n");
>
> /* Set bits of CONFIG register with dynamic context switching */
> - if (readl(sdma->regs + SDMA_H_CONFIG) == 0)
> - writel_relaxed(SDMA_H_CONFIG_CSM, sdma->regs + SDMA_H_CONFIG);
> + reg = readl(sdma->regs + SDMA_H_CONFIG);
> + if ((reg & SDMA_H_CONFIG_CSM) == 0) {
> + reg |= SDMA_H_CONFIG_CSM;
> + writel_relaxed(reg, sdma->regs + SDMA_H_CONFIG);
> + }
>
> return ret;
> }
> @@ -1840,6 +1845,9 @@ static int sdma_init(struct sdma_engine *sdma)
> if (ret)
> goto disable_clk_ipg;
>
> + if (clk_get_rate(sdma->clk_ahb) == clk_get_rate(sdma->clk_ipg))
> + sdma->clk_ratio = 1;
> +
> /* Be sure SDMA has not started yet */
> writel_relaxed(0, sdma->regs + SDMA_H_C0PTR);
>
> @@ -1880,8 +1888,10 @@ static int sdma_init(struct sdma_engine *sdma)
> writel_relaxed(0x4050, sdma->regs + SDMA_CHN0ADDR);
>
> /* Set bits of CONFIG register but with static context switching */
> - /* FIXME: Check whether to set ACR bit depending on clock ratios */
> - writel_relaxed(0, sdma->regs + SDMA_H_CONFIG);
> + if (sdma->clk_ratio)
> + writel_relaxed(SDMA_H_CONFIG_ACR, sdma->regs + SDMA_H_CONFIG);
> + else
> + writel_relaxed(0, sdma->regs + SDMA_H_CONFIG);
>
> writel_relaxed(ccb_phys, sdma->regs + SDMA_H_C0PTR);
>
