| Message ID | 20211110084950.1053426-2-u.kleine-koenig@pengutronix.de |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [1/3] pwm: lpc18xx-sct: Initialize driver data and hardware before pwmchip_add() | expand |
On Wed, Nov 10, 2021 at 09:49:49AM +0100, Uwe Kleine-König wrote: > Each devm allocations has an overhead of 24 bytes to store the related > struct devres_node additionally to the fragmentation of the allocator. > So allocating 16 struct lpc18xx_pwm_data (which only hold a single int) > adds quite some overhead. Instead put the per-channel data into the > driver data struct and allocate it in one go. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> > --- > drivers/pwm/pwm-lpc18xx-sct.c | 12 +++++------- > 1 file changed, 5 insertions(+), 7 deletions(-) This could've been merged with patch 3 to make it a bit more obvious why this is useful. Patch 2 itself is a bit half-baked without patch 3. But I'll apply these anyway. Thanks, Thierry
diff --git a/drivers/pwm/pwm-lpc18xx-sct.c b/drivers/pwm/pwm-lpc18xx-sct.c index 8cc8ae16553c..6cf02554066c 100644 --- a/drivers/pwm/pwm-lpc18xx-sct.c +++ b/drivers/pwm/pwm-lpc18xx-sct.c @@ -76,6 +76,8 @@ #define LPC18XX_PWM_EVENT_PERIOD 0 #define LPC18XX_PWM_EVENT_MAX 16 +#define LPC18XX_NUM_PWMS 16 + /* SCT conflict resolution */ enum lpc18xx_pwm_res_action { LPC18XX_PWM_RES_NONE, @@ -101,6 +103,7 @@ struct lpc18xx_pwm_chip { unsigned long event_map; struct mutex res_lock; struct mutex period_lock; + struct lpc18xx_pwm_data channeldata[LPC18XX_NUM_PWMS]; }; static inline struct lpc18xx_pwm_chip * @@ -370,7 +373,7 @@ static int lpc18xx_pwm_probe(struct platform_device *pdev) lpc18xx_pwm->chip.dev = &pdev->dev; lpc18xx_pwm->chip.ops = &lpc18xx_pwm_ops; - lpc18xx_pwm->chip.npwm = 16; + lpc18xx_pwm->chip.npwm = LPC18XX_NUM_PWMS; /* SCT counter must be in unify (32 bit) mode */ lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG, @@ -400,12 +403,7 @@ static int lpc18xx_pwm_probe(struct platform_device *pdev) pwm = &lpc18xx_pwm->chip.pwms[i]; - data = devm_kzalloc(lpc18xx_pwm->dev, sizeof(*data), - GFP_KERNEL); - if (!data) { - ret = -ENOMEM; - goto disable_pwmclk; - } + data = &lpc18xx_pwm->channeldata[i]; pwm_set_chip_data(pwm, data); }
Each devm allocations has an overhead of 24 bytes to store the related struct devres_node additionally to the fragmentation of the allocator. So allocating 16 struct lpc18xx_pwm_data (which only hold a single int) adds quite some overhead. Instead put the per-channel data into the driver data struct and allocate it in one go. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- drivers/pwm/pwm-lpc18xx-sct.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-)