diff options
| author | Uwe Kleine-König <u.kleine-koenig@pengutronix.de> | 2020-02-11 00:22:40 +0300 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2020-03-30 17:55:26 +0300 |
| commit | 2cb5cd90f4cd3f819178bb47f3d1ef86ce612db7 (patch) | |
| tree | 5d91a06bb57fa468a0245d1335192921998fa857 /drivers/pwm | |
| parent | 4563654fddc05a572f889373ba22abc616b3aa1f (diff) | |
| download | linux-2cb5cd90f4cd3f819178bb47f3d1ef86ce612db7.tar.xz | |
pwm: imx27: Ensure clocks being on iff the PWM is on
Up to now the .probe() function didn't enable clocks and relied on the
core to call the .get_state() callback to have the clock running. The
latter enabled the needed clocks and kept them running if the PWM wass
enabled.
This only works correctly if the .get_state() callback is called exactly
once and this single call happens before unused clocks are disabled by
the clk core.
The former wasn't true for a short period while commit 01ccf903edd6
("pwm: Let pwm_get_state() return the last implemented state") applied
and not reverted yet and might become wrong in the future.
The latter isn't true any more since commit cfc4c189bc70 ("pwm: Read
initial hardware state at request time") which results in a running PWM
being stopped at boot time if for example the consumer lives in a kernel
module that is only loaded after the clk core disabled unused clocks.
So ensure .probe() is left with the clocks on if the PWM is running and
.get_state() disables everything it enabled.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
| -rw-r--r-- | drivers/pwm/pwm-imx27.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c index fb142813d455..e83c077bb7cc 100644 --- a/drivers/pwm/pwm-imx27.c +++ b/drivers/pwm/pwm-imx27.c @@ -171,8 +171,7 @@ static void pwm_imx27_get_state(struct pwm_chip *chip, tmp = NSEC_PER_SEC * (u64)(val); state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, pwm_clk); - if (!state->enabled) - pwm_imx27_clk_disable_unprepare(imx); + pwm_imx27_clk_disable_unprepare(imx); } static void pwm_imx27_sw_reset(struct pwm_chip *chip) @@ -307,6 +306,8 @@ MODULE_DEVICE_TABLE(of, pwm_imx27_dt_ids); static int pwm_imx27_probe(struct platform_device *pdev) { struct pwm_imx27_chip *imx; + int ret; + u32 pwmcr; imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL); if (imx == NULL) @@ -349,6 +350,15 @@ static int pwm_imx27_probe(struct platform_device *pdev) if (IS_ERR(imx->mmio_base)) return PTR_ERR(imx->mmio_base); + ret = pwm_imx27_clk_prepare_enable(imx); + if (ret) + return ret; + + /* keep clks on if pwm is running */ + pwmcr = readl(imx->mmio_base + MX3_PWMCR); + if (!(pwmcr & MX3_PWMCR_EN)) + pwm_imx27_clk_disable_unprepare(imx); + return pwmchip_add(&imx->chip); } |