On 10/2/24 9:45 PM, Frank Li wrote:
On Sun, Sep 22, 2024 at 10:28:02PM +0200, Marek Vasut wrote:
Hi,
On 9/17/24 9:25 PM, Frank Li wrote:
[...]
@@ -223,6 +224,8 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
unsigned long long c;
unsigned long long clkrate;
+ unsigned long flags;
+ int val;
int ret;
u32 cr;
@@ -263,7 +266,69 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,
[...]
+ c = clkrate * 1500;
+ do_div(c, NSEC_PER_SEC);
+
+ local_irq_save(flags);
+ val = FIELD_GET(MX3_PWMSR_FIFOAV, readl_relaxed(imx->mmio_base + MX3_PWMSR));
I think the multi-write I mentioned in v5 for > 500 kHz case could further
improve the patch, let's see what others think:
if (state->period < 2000) { /* 2000ns = 500 kHz */
/* Best effort attempt to fix up >500 kHz case */
udelay(6); /* 2us per FIFO entry, 3 FIFO entries written => 6 us */
writel_relaxed(duty_cycles, imx->mmio_base + MX3_PWMSAR);
writel_relaxed(duty_cycles, imx->mmio_base + MX3_PWMSAR);
/* Last write is outside, after this conditional */
} else if (duty_cycles ...
Can you have a look at this part ?
+ if (duty_cycles < imx->duty_cycle && val < MX3_PWMSR_FIFOAV_2WORDS) {
+ val = readl_relaxed(imx->mmio_base + MX3_PWMCNR);
+ /*
+ * If counter is close to period, controller may roll over when
+ * next IO write.
+ */
c is only used in this if (duty_cycles ...) { } conditional, the do_div()
above can be moved here:
It is in local_irq_save(flags) scope, it'd better as less as possible. So
I prefer do_div() is outside local_irq_save()
Good point, either way is fine by me.
