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authorLokesh Vutla <lokeshvutla@ti.com>2020-03-12 09:52:07 +0530
committerThierry Reding <thierry.reding@gmail.com>2020-03-30 18:03:06 +0200
commit348fb6f7fb4cc7ebc35d1cde6e5c2ada64b683c6 (patch)
treed2acff110256705fac0caf344395d8b387062887 /drivers/pwm/pwm-omap-dmtimer.c
parent54091b5f195b45a9a7d394008c06d2b9646ab126 (diff)
pwm: omap-dmtimer: Update description for PWM OMAP DM timer
Update the description with a brief about how PWM is generated using OMAP DM timer and add limitations for the PWM generations. Also add a link to the reference manual. Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Tony Lindgren <tony@atomide.com> Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm/pwm-omap-dmtimer.c')
-rw-r--r--drivers/pwm/pwm-omap-dmtimer.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
index e4f5f710bfaa..92aac6c86b95 100644
--- a/drivers/pwm/pwm-omap-dmtimer.c
+++ b/drivers/pwm/pwm-omap-dmtimer.c
@@ -10,7 +10,15 @@
*
* Description:
* This file is the core OMAP support for the generic, Linux
- * PWM driver / controller, using the OMAP's dual-mode timers.
+ * PWM driver / controller, using the OMAP's dual-mode timers
+ * with a timer counter that goes up. When it overflows it gets
+ * reloaded with the load value and the pwm output goes up.
+ * When counter matches with match register, the output goes down.
+ * Reference Manual: http://www.ti.com/lit/ug/spruh73q/spruh73q.pdf
+ *
+ * Limitations:
+ * - When PWM is stopped, timer counter gets stopped immediately. This
+ * doesn't allow the current PWM period to complete and stops abruptly.
*/
#include <linux/clk.h>