Commit e866834c authored by Uwe Kleine-König's avatar Uwe Kleine-König Committed by Uwe Kleine-König
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pwm: Let pwm_set_waveform_might_sleep() fail for exact but impossible requests 



Up to now pwm_set_waveform_might_sleep() returned 1 for exact requests
that couldn't be served exactly. In contrast to
pwm_round_waveform_might_sleep() and pwm_set_waveform_might_sleep() with
exact = false this is an error condition. So simplify handling for
callers of pwm_set_waveform_might_sleep() by returning -EDOM instead of
1 in this case.

Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://lore.kernel.org/r/20538a46719584dafd8a1395c886780a97dcdf79.1746010245.git.u.kleine-koenig@baylibre.com


Signed-off-by: default avatarUwe Kleine-König <ukleinek@kernel.org>
parent 2006016e

drivers/pwm/core.c

+16 −5
Original line number Diff line number Diff line
@@ -404,15 +404,16 @@ static int __pwm_set_waveform(struct pwm_device *pwm, 
 * Typically a requested waveform cannot be implemented exactly, e.g. because

 * you requested .period_length_ns = 100 ns, but the hardware can only set

 * periods that are a multiple of 8.5 ns. With that hardware passing @exact =

 * true results in pwm_set_waveform_might_sleep() failing and returning 1. If

 * @exact = false you get a period of 93.5 ns (i.e. the biggest period not bigger

 * than the requested value).

 * true results in pwm_set_waveform_might_sleep() failing and returning -EDOM.

 * If @exact = false you get a period of 93.5 ns (i.e. the biggest period not

 * bigger than the requested value).

 * Note that even with @exact = true, some rounding by less than 1 ns is

 * possible/needed. In the above example requesting .period_length_ns = 94 and

 * @exact = true, you get the hardware configured with period = 93.5 ns.

 *

 * Returns: 0 on success, 1 if was rounded up (if !@exact) or no perfect match was

 * possible (if @exact), or a negative errno

 * Returns: 0 on success, 1 if was rounded up (if !@exact), -EDOM if setting

 * failed due to the exact waveform not being possible (if @exact), or a

 * different negative errno on failure.

 * Context: May sleep.

 */

int pwm_set_waveform_might_sleep(struct pwm_device *pwm,
@@ -440,6 +441,16 @@ int pwm_set_waveform_might_sleep(struct pwm_device *pwm, 
		err = __pwm_set_waveform(pwm, wf, exact);

	}



	/*

	 * map err == 1 to -EDOM for exact requests. Also make sure that -EDOM is

	 * only returned in exactly that case. Note that __pwm_set_waveform()

	 * should never return -EDOM which justifies the unlikely().

	 */

	if (unlikely(err == -EDOM))

		err = -EINVAL;

	else if (exact && err == 1)

		err = -EDOM;



	return err;

}

EXPORT_SYMBOL_GPL(pwm_set_waveform_might_sleep);