Re: [PATCH v9 3/4] pwm: add microchip soft ip corePWM driver
From: Conor.Dooley
Date: Mon Aug 22 2022 - 05:19:18 EST
On 22/08/2022 09:42, Dan Carpenter wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> Hi Conor,
>
> url: https://github.com/intel-lab-lkp/linux/commits/Conor-Dooley/Microchip-soft-ip-corePWM-driver/20220819-170106
> base: 568035b01cfb107af8d2e4bd2fb9aea22cf5b868
> config: arm64-randconfig-m031-20220821 (https://download.01.org/0day-ci/archive/20220821/202208212329.XETz1mt0-lkp@xxxxxxxxx/config)
> compiler: aarch64-linux-gcc (GCC) 12.1.0
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> smatch warnings:
> drivers/pwm/pwm-microchip-core.c:295 mchp_core_pwm_apply() warn: inconsistent returns '&mchp_core_pwm->lock'.
Totally correct, there's a missing unlock. I'll send a v10 at some stage this week.
Thanks Dan,
Conor.
>
> vim +295 drivers/pwm/pwm-microchip-core.c
>
> ae39414af22131 Conor Dooley 2022-08-19 200 static int mchp_core_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> ae39414af22131 Conor Dooley 2022-08-19 201 const struct pwm_state *state)
> ae39414af22131 Conor Dooley 2022-08-19 202 {
> ae39414af22131 Conor Dooley 2022-08-19 203 struct mchp_core_pwm_chip *mchp_core_pwm = to_mchp_core_pwm(chip);
> ae39414af22131 Conor Dooley 2022-08-19 204 struct pwm_state current_state = pwm->state;
> ae39414af22131 Conor Dooley 2022-08-19 205 bool period_locked;
> ae39414af22131 Conor Dooley 2022-08-19 206 u64 duty_steps;
> ae39414af22131 Conor Dooley 2022-08-19 207 u16 prescale;
> ae39414af22131 Conor Dooley 2022-08-19 208 u8 period_steps;
> ae39414af22131 Conor Dooley 2022-08-19 209 int ret;
> ae39414af22131 Conor Dooley 2022-08-19 210
> ae39414af22131 Conor Dooley 2022-08-19 211 mutex_lock(&mchp_core_pwm->lock);
> ae39414af22131 Conor Dooley 2022-08-19 212
> ae39414af22131 Conor Dooley 2022-08-19 213 if (!state->enabled) {
> ae39414af22131 Conor Dooley 2022-08-19 214 mchp_core_pwm_enable(chip, pwm, false, current_state.period);
> ae39414af22131 Conor Dooley 2022-08-19 215 mutex_unlock(&mchp_core_pwm->lock);
> ae39414af22131 Conor Dooley 2022-08-19 216 return 0;
> ae39414af22131 Conor Dooley 2022-08-19 217 }
> ae39414af22131 Conor Dooley 2022-08-19 218
> ae39414af22131 Conor Dooley 2022-08-19 219 /*
> ae39414af22131 Conor Dooley 2022-08-19 220 * If the only thing that has changed is the duty cycle or the polarity,
> ae39414af22131 Conor Dooley 2022-08-19 221 * we can shortcut the calculations and just compute/apply the new duty
> ae39414af22131 Conor Dooley 2022-08-19 222 * cycle pos & neg edges
> ae39414af22131 Conor Dooley 2022-08-19 223 * As all the channels share the same period, do not allow it to be
> ae39414af22131 Conor Dooley 2022-08-19 224 * changed if any other channels are enabled.
> ae39414af22131 Conor Dooley 2022-08-19 225 * If the period is locked, it may not be possible to use a period
> ae39414af22131 Conor Dooley 2022-08-19 226 * less than that requested. In that case, we just abort.
> ae39414af22131 Conor Dooley 2022-08-19 227 */
> ae39414af22131 Conor Dooley 2022-08-19 228 period_locked = mchp_core_pwm->channel_enabled & ~(1 << pwm->hwpwm);
> ae39414af22131 Conor Dooley 2022-08-19 229
> ae39414af22131 Conor Dooley 2022-08-19 230 if (period_locked) {
> ae39414af22131 Conor Dooley 2022-08-19 231 u16 hw_prescale;
> ae39414af22131 Conor Dooley 2022-08-19 232 u8 hw_period_steps;
> ae39414af22131 Conor Dooley 2022-08-19 233
> ae39414af22131 Conor Dooley 2022-08-19 234 mchp_core_pwm_calc_period(chip, state, (u8 *)&prescale, &period_steps);
> ae39414af22131 Conor Dooley 2022-08-19 235 hw_prescale = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PRESCALE);
> ae39414af22131 Conor Dooley 2022-08-19 236 hw_period_steps = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PERIOD);
> ae39414af22131 Conor Dooley 2022-08-19 237
> ae39414af22131 Conor Dooley 2022-08-19 238 if ((period_steps + 1) * (prescale + 1) <
> ae39414af22131 Conor Dooley 2022-08-19 239 (hw_period_steps + 1) * (hw_prescale + 1)) {
> ae39414af22131 Conor Dooley 2022-08-19 240 mutex_unlock(&mchp_core_pwm->lock);
> ae39414af22131 Conor Dooley 2022-08-19 241 return -EINVAL;
> ae39414af22131 Conor Dooley 2022-08-19 242 }
> ae39414af22131 Conor Dooley 2022-08-19 243
> ae39414af22131 Conor Dooley 2022-08-19 244 /*
> ae39414af22131 Conor Dooley 2022-08-19 245 * It is possible that something could have set the period_steps
> ae39414af22131 Conor Dooley 2022-08-19 246 * register to 0xff, which would prevent us from setting a 100%
> ae39414af22131 Conor Dooley 2022-08-19 247 * duty cycle, as explained in the mchp_core_pwm_calc_period()
> ae39414af22131 Conor Dooley 2022-08-19 248 * above.
> ae39414af22131 Conor Dooley 2022-08-19 249 * The period is locked and we cannot change this, so we abort.
> ae39414af22131 Conor Dooley 2022-08-19 250 */
> ae39414af22131 Conor Dooley 2022-08-19 251 if (period_steps == MCHPCOREPWM_PERIOD_STEPS_MAX)
> ae39414af22131 Conor Dooley 2022-08-19 252 return -EINVAL;
>
> mutex_unlock(&mchp_core_pwm->lock); before the retun?
>
> ae39414af22131 Conor Dooley 2022-08-19 253
> ae39414af22131 Conor Dooley 2022-08-19 254 prescale = hw_prescale;
> ae39414af22131 Conor Dooley 2022-08-19 255 period_steps = hw_period_steps;
> ae39414af22131 Conor Dooley 2022-08-19 256 } else if (!current_state.enabled || current_state.period != state->period) {
> ae39414af22131 Conor Dooley 2022-08-19 257 ret = mchp_core_pwm_calc_period(chip, state, (u8 *)&prescale, &period_steps);
> ae39414af22131 Conor Dooley 2022-08-19 258 if (ret) {
> ae39414af22131 Conor Dooley 2022-08-19 259 mutex_unlock(&mchp_core_pwm->lock);
> ae39414af22131 Conor Dooley 2022-08-19 260 return ret;
> ae39414af22131 Conor Dooley 2022-08-19 261 }
> ae39414af22131 Conor Dooley 2022-08-19 262 mchp_core_pwm_apply_period(mchp_core_pwm, prescale, period_steps);
> ae39414af22131 Conor Dooley 2022-08-19 263 } else {
> ae39414af22131 Conor Dooley 2022-08-19 264 prescale = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PRESCALE);
> ae39414af22131 Conor Dooley 2022-08-19 265 period_steps = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PERIOD);
> ae39414af22131 Conor Dooley 2022-08-19 266
> ae39414af22131 Conor Dooley 2022-08-19 267 /*
> ae39414af22131 Conor Dooley 2022-08-19 268 * As above, it is possible that something could have set the
> ae39414af22131 Conor Dooley 2022-08-19 269 * period_steps register to 0xff, which would prevent us from
> ae39414af22131 Conor Dooley 2022-08-19 270 * setting a 100% duty cycle, as explained above.
> ae39414af22131 Conor Dooley 2022-08-19 271 * As the period is not locked, we are free to fix this.
> ae39414af22131 Conor Dooley 2022-08-19 272 */
> ae39414af22131 Conor Dooley 2022-08-19 273 if (period_steps == MCHPCOREPWM_PERIOD_STEPS_MAX) {
> ae39414af22131 Conor Dooley 2022-08-19 274 period_steps -= 1;
> ae39414af22131 Conor Dooley 2022-08-19 275 mchp_core_pwm_apply_period(mchp_core_pwm, prescale, period_steps);
> ae39414af22131 Conor Dooley 2022-08-19 276 }
> ae39414af22131 Conor Dooley 2022-08-19 277 }
> ae39414af22131 Conor Dooley 2022-08-19 278
> ae39414af22131 Conor Dooley 2022-08-19 279 duty_steps = mchp_core_pwm_calc_duty(chip, pwm, state, prescale, period_steps);
> ae39414af22131 Conor Dooley 2022-08-19 280
> ae39414af22131 Conor Dooley 2022-08-19 281 /*
> ae39414af22131 Conor Dooley 2022-08-19 282 * Because the period is per channel, it is possible that the requested
> ae39414af22131 Conor Dooley 2022-08-19 283 * duty cycle is longer than the period, in which case cap it to the
> ae39414af22131 Conor Dooley 2022-08-19 284 * period, IOW a 100% duty cycle.
> ae39414af22131 Conor Dooley 2022-08-19 285 */
> ae39414af22131 Conor Dooley 2022-08-19 286 if (duty_steps > period_steps)
> ae39414af22131 Conor Dooley 2022-08-19 287 duty_steps = period_steps + 1;
> ae39414af22131 Conor Dooley 2022-08-19 288
> ae39414af22131 Conor Dooley 2022-08-19 289 mchp_core_pwm_apply_duty(chip, pwm, state, duty_steps, period_steps);
> ae39414af22131 Conor Dooley 2022-08-19 290
> ae39414af22131 Conor Dooley 2022-08-19 291 mchp_core_pwm_enable(chip, pwm, true, state->period);
> ae39414af22131 Conor Dooley 2022-08-19 292
> ae39414af22131 Conor Dooley 2022-08-19 293 mutex_unlock(&mchp_core_pwm->lock);
> ae39414af22131 Conor Dooley 2022-08-19 294
> ae39414af22131 Conor Dooley 2022-08-19 @295 return 0;
> ae39414af22131 Conor Dooley 2022-08-19 296 }
>
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