Messages in this thread | | | From | Robert Jarzmik <> | Subject | Re: [PATCH] Revert "backlight: pwm: Handle EPROBE_DEFER while requesting the PWM" | Date | Thu, 01 Oct 2015 11:06:33 +0200 |
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Nicolas Ferre <nicolas.ferre@atmel.com> writes:
> Le 30/09/2015 21:29, Robert Jarzmik a écrit : >> Robert Jarzmik <robert.jarzmik@free.fr> writes: >> >>> This reverts commit 68feaca0b13e453aa14ee064c1736202b48b342f. >>> This commit breaks legacy platforms, for which : >>> (a) no pwm table is added (legacy platforms) >>> (b) in this case, in pwm_get(), pmw_lookup_list is empty, and therefore >>> chosen == NULL, and therefore pwm_get() returns NULL, and pwm_get() >>> returns -EPROBE_DEFER >>> (c) as a consequence, this code is unreachable in pwm_bl.c : >>> if (IS_ERR(pb->pwm)) { >>> ret = PTR_ERR(pb->pwm); >>> dev_info(&pdev->dev, "%s:%d(): %d\n", __func__, __LINE__, ret); >>> if (ret == -EPROBE_DEFER) >>> goto err_alloc; >>> >>> dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n"); >>> pb->legacy = true; >>> pb->pwm = pwm_request(data->pwm_id, "pwm-backlight"); >>> >>> As this code is unreachable, all legacy platforms relying on pwm_id are >>> broken, amongst which pxa have been tested as broken. >>> >>> Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr> >> Thierry, would you have a look please ? >> As I said before, all legacy platform relying on pwm_id are broken. I'd like to >> be sure this lands in the next -rc series. > > Well, as I answered on the linux-pwm mailing-list (I was not in copy) here: > http://article.gmane.org/gmane.linux.pwm/2744 > I wonder if it's not easier to fix the platforms and add the pwm tables... No it's not, at least not for a -rc cycle. It's the long term solution you're talking about, not the fix one.
> Otherwise, Boris proposed this fix: > 8<----------------------------------------------------------- > diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c > index eff379b..00483d4 100644 > --- a/drivers/video/backlight/pwm_bl.c > +++ b/drivers/video/backlight/pwm_bl.c > @@ -273,15 +273,15 @@ static int pwm_backlight_probe(struct platform_device *pdev) > pb->pwm = devm_pwm_get(&pdev->dev, NULL); > if (IS_ERR(pb->pwm)) { > ret = PTR_ERR(pb->pwm); > - if (ret == -EPROBE_DEFER) > - goto err_alloc; > > dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n"); > pb->legacy = true; > pb->pwm = pwm_request(data->pwm_id, "pwm-backlight"); > if (IS_ERR(pb->pwm)) { > dev_err(&pdev->dev, "unable to request legacy PWM\n"); > - ret = PTR_ERR(pb->pwm); > + if (ret != -EPROBE_DEFER) > + ret = PTR_ERR(pb->pwm); > + > goto err_alloc; > } > } > > which is not tested and may add an extra non-valid error log. I can test that, today, it looks an interesting alternative.
If both solutions do work, someone (Boris) can post a patch for this -rc instead of the revert. If no patch is posted, I maintain my Revert, as this patch _does_ break platforms (omap is broken too AFAICS).
Cheers.
-- Robert
PS: I have not received http://article.gmane.org/gmane.linux.pwm/2744. Is it my mailer or MUA which is broken, ie. was I in the "To:" of the mail ?
PPS: Sorry to having forgotten to join you to the revert
PPPS: As long as an other patch is not submitted to fix the issue (other than the Revert), I NAK the NAK. There is a breakage introduced, and I consider it a strong enough reason to be maintained for the -rc serie.
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