Hi Lucas,
On 2019-01-21 02:17, Lucas Stach wrote:
Hi Angus,
Am Samstag, den 19.01.2019, 19:31 -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
> Signed-off-by: Angus Ainslie (Purism) <angus@xxxxxxxx>
---
.../devicetree/bindings/dma/fsl-imx-sdma.txt | 1 +
drivers/dma/imx-sdma.c | 20
+++++++++++++++----
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt
b/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt
index 3c9a57a8443b..17544c1820b7 100644
--- a/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt
+++ b/Documentation/devicetree/bindings/dma/fsl-imx-sdma.txt
@@ -67,6 +67,7 @@ Optional properties:
reg is the GPR register offset.
shift is the bit position inside the GPR register.
val is the value of the bit (0 or 1).
+- fsl,ratio-1-1: AHB/SDMA core clock ration 1:1, 2:1 without this.
Why does this need a separate DT property? Shouldn't the driver be able
to infer this from the clock rates going into the SDMA hardware?
That's probably a better way to do it then setting the property can't
get missed. I'll address it in v3.
Angus
Regards,
Lucas
Examples:
diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 0b3a67ff8e82..65dada21d3c1 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 +664,14 @@ 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);
> + if (readl(sdma->regs + SDMA_H_CONFIG) == 0) {
> + if (sdma->clk_ratio)
> + reg = SDMA_H_CONFIG_CSM | SDMA_H_CONFIG_ACR;
> + else
> + reg = SDMA_H_CONFIG_CSM;
+
> + writel_relaxed(reg, sdma->regs + SDMA_H_CONFIG);
> + }
> return ret;
}
@@ -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);
@@ -1975,6 +1985,8 @@ static int sdma_probe(struct platform_device
*pdev)
> if (!sdma)
> return -ENOMEM;
> + sdma->clk_ratio = of_property_read_bool(np, "fsl,ratio-1-1");
+
> spin_lock_init(&sdma->channel_0_lock);
> sdma->dev = &pdev->dev;
