Commit bd88d319 authored by Thierry Reding's avatar Thierry Reding
Browse files

pwm: imx27: Unconditionally write state to hardware 



The i.MX driver currently uses a shortcut and doesn't write all of the
state through to the hardware when the PWM is disabled. This causes an
inconsistent state to be read back by consumers with the result of them
malfunctioning.

Fix this by always writing the full state through to the hardware
registers so that the correct state can always be read back.

Tested-by: default avatarMichal Vokáč <michal.vokac@ysoft.com>
Tested-by: default avatarAdam Ford <aford173@gmail.com>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent a3597d6c

drivers/pwm/pwm-imx27.c

+59 −61
Original line number Diff line number Diff line
@@ -230,7 +230,6 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm, 


	pwm_get_state(pwm, &cstate);



	if (state->enabled) {

	c = clk_get_rate(imx->clk_per);

	c *= state->period;
@@ -245,8 +244,8 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm, 
	duty_cycles = c;



	/*

		 * according to imx pwm RM, the real period value should be

		 * PERIOD value in PWMPR plus 2.

	 * according to imx pwm RM, the real period value should be PERIOD

	 * value in PWMPR plus 2.

	 */

	if (period_cycles > 2)

		period_cycles -= 2;
@@ -254,9 +253,8 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm, 
		period_cycles = 0;



	/*

		 * Wait for a free FIFO slot if the PWM is already enabled, and

		 * flush the FIFO if the PWM was disabled and is about to be

		 * enabled.

	 * Wait for a free FIFO slot if the PWM is already enabled, and flush

	 * the FIFO if the PWM was disabled and is about to be enabled.

	 */

	if (cstate.enabled) {

		pwm_imx27_wait_fifo_slot(chip, pwm);
@@ -272,27 +270,27 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm, 
	writel(period_cycles, imx->mmio_base + MX3_PWMPR);



	/*

		 * Store the duty cycle for future reference in cases where

		 * the MX3_PWMSAR register can't be read (i.e. when the PWM

		 * is disabled).

	 * Store the duty cycle for future reference in cases where the

	 * MX3_PWMSAR register can't be read (i.e. when the PWM is disabled).

	 */

	imx->duty_cycle = duty_cycles;



	cr = MX3_PWMCR_PRESCALER_SET(prescale) |

	     MX3_PWMCR_STOPEN | MX3_PWMCR_DOZEN | MX3_PWMCR_WAITEN |

	     FIELD_PREP(MX3_PWMCR_CLKSRC, MX3_PWMCR_CLKSRC_IPG_HIGH) |

		     MX3_PWMCR_DBGEN | MX3_PWMCR_EN;

	     MX3_PWMCR_DBGEN;



	if (state->polarity == PWM_POLARITY_INVERSED)

		cr |= FIELD_PREP(MX3_PWMCR_POUTC,

				MX3_PWMCR_POUTC_INVERTED);



	if (state->enabled)

		cr |= MX3_PWMCR_EN;



	writel(cr, imx->mmio_base + MX3_PWMCR);

	} else if (cstate.enabled) {

		writel(0, imx->mmio_base + MX3_PWMCR);



	if (!state->enabled && cstate.enabled)

		pwm_imx27_clk_disable_unprepare(chip);

	}



	return 0;

}

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