Hi Thierry,
See the comments below.
> I think the correct capitalizations are: "Freescale", "FTM" and "PWM".
> There are other occurrences in the rest of the driver that I haven't
> explicitly pointed out.
>
Yes, that's much better.
> > +config PWM_FTM
>
> Perhaps name this PWM_FSL_FTM to match the driver name?
>
OK.
> And fix this up to be "pwm-fsl-ftm".
Yes, I will.
> > +#define FTM_CSC_BASE 0x0C
> > +#define FTM_CSC(_CHANNEL) \
> > + (FTM_CSC_BASE + (_CHANNEL * 0x08))
>
> I prefer lowercase variables in macros:
>
> #define FTM_CSC(channel) \
> (FTM_CSC_BASE + (channel * 8))
>
Yes, That's better.
> > +#define FTM_PWMMODE (FTMCnSC_MSB)
> > +#define FTM_HIGH_TRUE (FTMCnSC_ELSB)
> > +#define FTM_LOW_TRUE (FTMCnSC_ELSA)
>
> What's the reason for redefining these? Can't you just use the FTMCnSC_*
> defines directly?
>
Just for more readable and comprehension.
I will revise it by not losing above two key elements.
> > +#define FTM_CV(_CHANNEL) \
> > + (FTM_CV_BASE + (_CHANNEL * 0x08))
>
> Same comment as for FTM_CSC above.
>
Yes.
> > +#define FTM_MAX_CHANNEL 0x08
>
> There should be no need for this. The only place where you use this is
> when assigning it to pwm_chip.npwm, so you may as well use the literal
> there.
>
I have recoded the driver, and the macro is used more than one time now.
> > + struct platform_device *pdev;
>
> You never use this platform_device. And you have to assign &pdev->dev to
> the pwm_chip.dev anyway, so why not just use that consistently and drop
> the pdev field?
>
Yes, I have droped the pdev field now.
> > + unsigned int cpwm;
> > + struct fsl_pwm fpwms[FTM_MAX_CHANNEL];
>
> Please don't do this. Use pwm_set_chip_data()/pwm_get_chip_data() to
> associate per-channel specific data.
>
I have replaced them now.
> > + /* pinctrl handles */
>
> Nit: it's only a single handle.
>
Yes.
> > + struct pinctrl *pinctrl;
>
> You also use tabs and spaces inconsistently here. I suggest you use a
> single space between the data type and the field name, that way it's much
> easier to stay consistent.
>
Now I have revised all about this.
> > +static int fsl_pwm_request_channel(struct pwm_chip *chip,
> > + struct pwm_device *pwm)
>
> The arguments on the trailing line aren't properly aligned. They should
> be aligned with the arguments on the first line.
>
The same as the above comment.
> > + ret = clk_prepare_enable(fpc->clk);
>
> This should probably be just clk_prepare(). Or is there some reason why
> you can't delay clk_enable() to the .enable() operation?
>
Firstly, we should be clear that the fpc->clk is chip's work clock.
If so, after the .request() is called and before .enable() is called, the custumer will call .config(),
in which will read/write the pwm chip registers, if the module clock is still disabled, then the system will hang up.
> > +static int fsl_updata_config(struct fsl_pwm_chip *fpc,
> > + struct pwm_device *pwm)
>
> Parameter alignment again. Please also check all other functions.
>
Yes, I have revise all about this.
> > +{
> > + int i;
>
> This should be unsigned int.
>
I will revise it.
> > +static unsigned long
> > +fsl_rate_to_cycles(struct fsl_pwm_chip *fpc, int time_ns)
>
> The above two lines are 78 characters when joined, so there's no need to
> split them.
>
OK, I have revise all about this.
> Perhaps time_ns should be "unsigned long"?
>
Shouldn't this be same with "int duty_ns" and "int period_ns", which are defined by
struct pwm_ops {
...
int (*config)(struct pwm_chip *chip,
struct pwm_device *pwm,
int duty_ns, int period_ns);
...
} ?
> > + ps = (0x01 << fpc->clk_ps);
>
> This is fairly short, so you could do it along with the variable
> declaration. Also there's no need for the parentheses or the hexadecimal
> prefix (0x01 == 1):
>
> unsigned long ps = 1 << fpc->clk_ps;
>
OK, I will revise it then.
> > + /* The module clk is HZ/s, the time_ns parameter
> > + * is based nanosecond, so here should divide
> > + * 1000000000UL.
> > + */
>
> Block comments should be:
>
> /*
> * ...
> * ...
> */
>
> Also HZ/s isn't a valid unit for a clock frequency. And time_ns also has
> the _ns suffix to designate the unit, so as a whole that comment doesn't
> add any real information and can just as well be dropped.
>
I will revise it.
> > +static int fsl_pwm_config_channel(struct pwm_chip *chip,
>
> I think you can safely drop the _channel suffix from the PWM operations.
>
By adding _channel suffix just for more comprehensave about the pwm's muti-channel operation.
If this is redundant here, I will drop it.
> > + fpc = to_fsl_chip(chip);
> > +
> > + if (WARN_ON(!test_bit(PWMF_REQUESTED, &pwm->flags)))
> > + return -ESHUTDOWN;
>
> Erm... how do you think this could ever happen? Users need to request a
> PWM to obtain a struct pwm_device, in which case PWMF_REQUESTED will
> always be set. There are a few other occurrences throughout the rest of
> the driver that I haven't pointed out explicitly.
>
Does the following case is exist ?
The customer in one thread has .free(pwm_1), while in another thread,
which maybe had slept in for some reason, will call .config/.enable/.disable?
If so, as I have explained before, if the pwm_1 has been freed, the module clock maybe
disabled too, so if the .config is call the system will hang up.
> > + fpc->fpwms[pwm->hwpwm].period_cycles = period_cycles;
> > + fpc->fpwms[pwm->hwpwm].duty_cycles = duty_cycles;
>
> You use these for the sole purpose of passing them into the
> fsl_updata_config() function, so I wonder why you can't just pass them as
> parameters and get rid of struct fsl_pwm as a bonus?
>
Before I think the fpc has all the information the fsl_update_config() function needed.
Now, I have dropt the fsl_update_config() function.
> > + fsl_updata_config(fpc, pwm);
>
> And now that I think about it: perhaps this was supposed to be called
> fsl_update_config() instead of fsl_updat*a*_config()?
>
Well, a written mistake.
> > + reg &= ~(0x01 << pwm->hwpwm);
>
> This would be slightly more canonical as:
>
> reg &= ~BIT(pwm->hwpwm);
>
Yes, looks much better.
> > + reg |= (polarity << pwm->hwpwm);
>
> And perhaps here it would be better to be explicit. I think it's unlikely
> that enum pwm_polarity will even gain a third entry, but better be safe
> than sorry:
>
> if (polarity == PWM_POLARITY_INVERSED)
> reg |= BIT(pwm->hwpwm);
> else
> reg &= ~BIT(pwm->hwpwm);
>
I will think it over.
While only the polarity's bit0 is used for polarity's statement. If other bit won't has any other
meaning and purpose in the feature, I will replace it derictly.
> > +static int is_any_other_channel_enabled(struct pwm_chip *chip,
> > + unsigned int cur)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < chip->npwm; i++) {
> > + if (i == cur)
> > + continue;
> > + if (test_bit(PWMF_ENABLED, &chip->pwms[i].flags))
> > + return 1;
> > + }
> > +
> > + return 0;
> > +}
>
> This can probably be better done using a reference/enable count. Instead
> of having to iterate over all PWM channels of the chip and checking their
> flags, just keep track of how many times .enable() and .disable() are
> called.
>
> To make it easier you can probably wrap that into two functions, such as
> fsl_clock_enable() and fsl_clock_disable().
>
> > +static int fsl_pwm_enable_channel(struct pwm_chip *chip,
> > + struct pwm_device *pwm)
> > +{
> [...]
> > + if (is_any_other_channel_enabled(chip, pwm->hwpwm))
> > + return 0;
>
> This is where you'd call fsl_clock_enable()...
>
> > + reg = readl(fpc->base + FTM_SC);
> > + reg &= ~((FTMSC_CLK_MASK << FTMSC_CLK_OFFSET) |
> > + (FTMSC_PS_MASK << FTMSC_PS_OFFSET));
> > + /* select system clock source */
> > + reg |= (FTMSC_CLKSYS | fpc->clk_ps);
> > + writel(reg, fpc->base + FTM_SC);
>
> ... and run this code in fsl_clock_enable() if the enable count is 0 to
> select the system clock when the first PWM is enabled.
>
> > +static void fsl_pwm_disable_channel(struct pwm_chip *chip,
> > + struct pwm_device *pwm)
> > +{
> [...]
> > + if (is_any_other_channel_enabled(chip, pwm->hwpwm))
> > + return;
>
> Then call fsl_clock_disable() here...
>
> > + writel(0xFF, fpc->base + FTM_OUTMASK);
> > + reg = readl(fpc->base + FTM_SC);
> > + reg &= ~(FTMSC_CLK_MASK << FTMSC_CLK_OFFSET);
> > + writel(reg, fpc->base + FTM_SC);
>
> ... and run this code in fsl_clock_disable() if the enable count reaches
> 0 so that the clock is disabled when no PWM channels remain on.
>
I will think it over and recode about this.
> > +static int fsl_pwm_parse_dt(struct fsl_pwm_chip *fpc) {
> [...]
> > + int ret = 0;
> > + u32 chs[FTM_MAX_CHANNEL];
> > + struct device_node *np = fpc->pdev->dev.of_node;
> > +
> > + ret = of_property_read_u32(np, "fsl,pwm-clk-ps",
> > + &fpc->clk_ps);
> > + if (ret < 0) {
> > + dev_err(&fpc->pdev->dev,
> > + "failed to get pwm "
> > + "clk prescaler : %d\n",
> > + ret);
>
> Perhaps it's more useful to mention the missing property explicitly in
> the error message:
>
> dev_err(fpc->chip.dev,
> "failed to parse \"fsl,pwm-clk-ps\" property: %d\n",
> ret);
>
Whil I think the following is better in code.
dev_err(fpc->chip.dev,
"failed to parse <fsl,pwm-clk-ps> property: %d\n",
ret);
>
> > + return ret;
> > + }
> > + if (fpc->clk_ps > 7 || fpc->clk_ps < 0)
>
> clk_ps is unsigned and therefore can't be < 0. And a blank line would be
> useful between the previous line ("}") and this line.
>
I will revise it.
> > +static int fsl_pwm_probe(struct platform_device *pdev) {
> > + int ret = 0;
> > + struct fsl_pwm_chip *fpc;
> > + struct resource *res;
> > +
> > + fpc = devm_kzalloc(&pdev->dev, sizeof(*fpc), GFP_KERNEL);
> > + if (!fpc) {
> > + dev_err(&pdev->dev,
> > + "failed to allocate memory\n");
>
> I don't think that's very useful either. If this should indeed ever fail,
> then the driver core will complain about the probe failing and include
> the error code. Since it's the only location where you return that error
> code you know immediately what went wrong.
>
Yes, for the devm_kzlloc() have print out the fail reason, this will be redundant.
I have revised all about this.
> > + return -ENOMEM;
> > + }
> > +
> > + mutex_init(&fpc->lock);
> > +
> > + fpc->pdev = pdev;
> > +
> > + ret = fsl_pwm_parse_dt(fpc);
> > + if (ret < 0)
> > + return ret;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + fpc->base = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(fpc->base)) {
> > + dev_err(&pdev->dev,
> > + "failed to ioremap() registers\n");
>
> No need for this error message. devm_ioremap_resource() prints out errors
> already on failure.
>
The same comment as the last one.
> > + fpc->chip.dev = &pdev->dev;
> > + fpc->chip.ops = &fsl_pwm_ops;
> > + fpc->chip.of_xlate = of_pwm_xlate_with_flags;
> > + fpc->chip.of_pwm_n_cells = 3;
> > + fpc->chip.base = -1;
> > +
> > + ret = pwmchip_add(&fpc->chip);
> > + if (ret < 0) {
> > + dev_err(&pdev->dev,
> > + "failed to add ftm0 pwm chip %d\n",
> > + ret);
>
> dev_err() will already include the device name in the error message, so I
> don't think you need the "ftm0" here. Also make sure to use the correct
> capitalization for "PWM". And there is no need to split this over so many
> lines, it all fits on a single line just fine. There are other
> occurrences of this, so please double-check.
>
Yes.
I have revise all about this.
Thanks very much.
--
Best Regards.
Xiubo
--
To unsubscribe from this list: send the line "unsubscribe linux-doc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
