pwm: sti: Reduce number of allocations and drop usage of chip_data

Instead of using one allocation per capture channel, use a single one. Also
store it in driver data instead of chip data.

This has several advantages:

 - driver data isn't cleared when pwm_put() is called
 - Reduces memory fragmentation

Also register the pwm chip only after the per capture channel data is
initialized as the capture callback relies on this initialization and it
might be called even before pwmchip_add() returns.

It would be still better to have struct sti_pwm_compat_data and the
per-channel data struct sti_cpt_ddata in a single memory chunk, but that's
not easily possible because the number of capture channels isn't known yet
when the driver data struct is allocated.

Fixes: e926b12c611c ("pwm: Clear chip_data in pwm_put()")
Reported-by: George Stark <gnstark@sberdevices.ru>
Fixes: c97267ae831d ("pwm: sti: Add PWM capture callback")
Link: https://lore.kernel.org/r/20230705080650.2353391-7-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 5756f2e3b3c0b5982a9aa43f91f63a6fb66b75b6..dc92cea31cd0782021c13fe7064e249b111a4efb 100644 (file)
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -79,6 +79,7 @@ struct sti_pwm_compat_data {
        unsigned int cpt_num_devs;
        unsigned int max_pwm_cnt;
        unsigned int max_prescale;
+       struct sti_cpt_ddata *ddata;
 };
 
 struct sti_pwm_chip {
@@ -314,7 +315,7 @@ static int sti_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm,
 {
        struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
        struct sti_pwm_compat_data *cdata = pc->cdata;
-       struct sti_cpt_ddata *ddata = pwm_get_chip_data(pwm);
+       struct sti_cpt_ddata *ddata = &cdata->ddata[pwm->hwpwm];
        struct device *dev = pc->dev;
        unsigned int effective_ticks;
        unsigned long long high, low;
@@ -439,7 +440,7 @@ static irqreturn_t sti_pwm_interrupt(int irq, void *data)
        while (cpt_int_stat) {
                devicenum = ffs(cpt_int_stat) - 1;
 
-               ddata = pwm_get_chip_data(&pc->chip.pwms[devicenum]);
+               ddata = &pc->cdata->ddata[devicenum];
 
                /*
                 * Capture input:
@@ -637,30 +638,28 @@ static int sti_pwm_probe(struct platform_device *pdev)
                        dev_err(dev, "failed to prepare clock\n");
                        return ret;
                }
+
+               cdata->ddata = devm_kzalloc(dev, cdata->cpt_num_devs * sizeof(*cdata->ddata), GFP_KERNEL);
+               if (!cdata->ddata)
+                       return -ENOMEM;
        }
 
        pc->chip.dev = dev;
        pc->chip.ops = &sti_pwm_ops;
        pc->chip.npwm = pc->cdata->pwm_num_devs;
 
-       ret = pwmchip_add(&pc->chip);
-       if (ret < 0) {
-               clk_unprepare(pc->pwm_clk);
-               clk_unprepare(pc->cpt_clk);
-               return ret;
-       }
-
        for (i = 0; i < cdata->cpt_num_devs; i++) {
-               struct sti_cpt_ddata *ddata;
-
-               ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
-               if (!ddata)
-                       return -ENOMEM;
+               struct sti_cpt_ddata *ddata = &cdata->ddata[i];
 
                init_waitqueue_head(&ddata->wait);
                mutex_init(&ddata->lock);
+       }
 
-               pwm_set_chip_data(&pc->chip.pwms[i], ddata);
+       ret = pwmchip_add(&pc->chip);
+       if (ret < 0) {
+               clk_unprepare(pc->pwm_clk);
+               clk_unprepare(pc->cpt_clk);
+               return ret;
        }
 
        platform_set_drvdata(pdev, pc);