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Subject[PATCH 2/4] dmaengine: imx-sdma: Add clock ratio 1:1 check
Date
On imx8mq B0 chip, AHB/SDMA clock ratio 2:1 can't be supported,
since SDMA clock ratio has to be increased to 250Mhz, AHB can't reach
to 500Mhz, so use 1:1 instead.

To limit this change to the imx8mq for now this patch also adds an
im8mq-sdma compatible string.

Signed-off-by: Angus Ainslie (Purism) <angus@akkea.ca>
---
drivers/dma/imx-sdma.c | 31 +++++++++++++++++++++++++++----
1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 7fae4bf885d5..99d9f431ae2c 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -419,6 +419,7 @@ struct sdma_driver_data {
int chnenbl0;
int num_events;
struct sdma_script_start_addrs *script_addrs;
+ bool check_ratio;
};

struct sdma_engine {
@@ -441,6 +442,8 @@ 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,
@@ -555,6 +558,13 @@ static struct sdma_driver_data sdma_imx7d = {
.script_addrs = &sdma_script_imx7d,
};

+static struct sdma_driver_data sdma_imx8mq = {
+ .chnenbl0 = SDMA_CHNENBL0_IMX35,
+ .num_events = 48,
+ .script_addrs = &sdma_script_imx7d,
+ .check_ratio = 1,
+};
+
static const struct platform_device_id sdma_devtypes[] = {
{
.name = "imx25-sdma",
@@ -577,6 +587,9 @@ static const struct platform_device_id sdma_devtypes[] = {
}, {
.name = "imx7d-sdma",
.driver_data = (unsigned long)&sdma_imx7d,
+ }, {
+ .name = "imx8mq-sdma",
+ .driver_data = (unsigned long)&sdma_imx8mq,
}, {
/* sentinel */
}
@@ -591,6 +604,7 @@ static const struct of_device_id sdma_dt_ids[] = {
{ .compatible = "fsl,imx31-sdma", .data = &sdma_imx31, },
{ .compatible = "fsl,imx25-sdma", .data = &sdma_imx25, },
{ .compatible = "fsl,imx7d-sdma", .data = &sdma_imx7d, },
+ { .compatible = "fsl,imx8mq-sdma", .data = &sdma_imx8mq, },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, sdma_dt_ids);
@@ -663,8 +677,11 @@ 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;
}
@@ -1847,6 +1864,10 @@ static int sdma_init(struct sdma_engine *sdma)
if (ret)
goto disable_clk_ipg;

+ if (sdma->drvdata->check_ratio &&
+ (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);

@@ -1887,8 +1908,10 @@ 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);

--
2.17.1
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