[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20230712100007.xltypsvcp7at5gg5@pengutronix.de>
Date: Wed, 12 Jul 2023 12:00:07 +0200
From: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To: Guiting Shen <aarongt.shen@...il.com>
Cc: claudiu.beznea@...rochip.com, thierry.reding@...il.com,
nicolas.ferre@...rochip.com, alexandre.belloni@...tlin.com,
linux-arm-kernel@...ts.infradead.org, linux-pwm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] pwm: atmel: Enable clk when pwm already enabled in
bootloader
On Wed, Jul 12, 2023 at 09:45:08AM +0800, Guiting Shen wrote:
> On Wed, Jul 12, 2023 at 04:30:17AM GMT+8, Uwe Kleine-König wrote:
> > Hello,
> >
> > On Wed, Jul 12, 2023 at 04:09:05AM +0800, Guiting Shen wrote:
> >> +static int atmel_pwm_enable_clk_if_on(struct atmel_pwm_chip *atmel_pwm)
> >> +{
> >> + unsigned int i;
> >> + int err;
> >> + u32 sr;
> >> +
> >> + sr = atmel_pwm_readl(atmel_pwm, PWM_SR);
> >> + if (!sr)
> >> + return 0;
> >> +
> >> + for (i = 0; i < atmel_pwm->chip.npwm; i++) {
> >> + if (!(sr & (1 << i)))
> >> + continue;
> >> +
> >> + err = clk_enable(atmel_pwm->clk);
> >> + if (err) {
> >> + dev_err(atmel_pwm->chip.dev,
> >> + "failed to enable clock: %pe\n", ERR_PTR(err));
> >
> > Here you leak possibly a few enables. While it's not likely that the
> > (say) third enable goes wrong, it's also not that hard to handle?!
>
> The driver used the enable_count member of struct clk_core to count the
> PWM channels(4 channels). It will enable hardware clock only when one of
> the PWM channels becomed on from all PWM channels off which maybe return
> error. And in second/third/fourth times to clk_enable(), it just
> increased the enable_count of struct clk_core which would never return
> error.
>
> It maybe confused at first time to view the code.
> Do it need to add something like that: ?
>
> for (i = 0; i < atmel_pwm->chip.npwm; i++) {
> if (!(sr & (1 << i)))
> continue;
>
> err = clk_enable(atmel_pwm->clk);
> if (err) {
> dev_err(atmel_pwm->chip.dev,
> "failed to enable clock: %pe\n", ERR_PTR(err));
>
> for (i = 0; i < cnt; i++)
> clk_disable(atmel_pwm->clk);
> return err;
> }
> cnt++;
> }
Yes, that approx. what I thought of. Maybe also mention i in the error
message? (So something like:
"failed to enable clock for pwm #%d: %pe\n"
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
Download attachment "signature.asc" of type "application/pgp-signature" (489 bytes)
Powered by blists - more mailing lists