On Monday 22 of July 2013 22:56:44 Daniel Lezcano wrote: > On 07/22/2013 09:43 AM, Tomasz Figa wrote: > > On Monday 22 of July 2013 05:50:09 Daniel Lezcano wrote: > >> On 07/20/2013 02:04 AM, Tomasz Figa wrote: > >>> PWM channel 4 has its autoreload bit located at different position. > >>> This patch fixes the driver to account for that. > >>> > >>> This fixes a problem with the clocksource hanging after it overflows > >>> because it is not reloaded any more. > >>> > >>> Signed-off-by: Tomasz Figa <[email protected]> > >>> --- > >>> > >>> drivers/clocksource/samsung_pwm_timer.c | 3 ++- > >>> 1 file changed, 2 insertions(+), 1 deletion(-) > >>> > >>> diff --git a/drivers/clocksource/samsung_pwm_timer.c > >>> b/drivers/clocksource/samsung_pwm_timer.c index 3fa5b07..e238fb0 > >>> 100644 > >>> --- a/drivers/clocksource/samsung_pwm_timer.c > >>> +++ b/drivers/clocksource/samsung_pwm_timer.c > >>> @@ -47,7 +47,8 @@ > >>> > >>> #define TCON_START(chan) (1 << (4 * (chan) + 0)) > >>> #define TCON_MANUALUPDATE(chan) (1 << (4 * (chan) + 1)) > >>> #define TCON_INVERT(chan) (1 << (4 * (chan) + 2)) > >>> > >>> -#define TCON_AUTORELOAD(chan) (1 << (4 * (chan) + 3)) > >>> +#define TCON_AUTORELOAD(chan) (1 << (4 * (chan) \ > >>> + + (((chan) < 5) ? 3 : 2))) > >> > >> This macro is not readable. Please, fix it up with a comment please. > > > > /* > > > > * Channel 4 (logically 5 in TCON register) has different position > > * of autoreload bit. > > */ > > > > #define _TCON_AUTORELOAD(chan) (1 << (4 * (chan) + 3)) > > #define _TCON_AUTORELOAD4(chan) (1 << (4 * (chan) + 2)) > > #define TCON_AUTORELOAD(chan) ((chan < 5) ? > > > > _TCON_AUTORELOAD(chan) : _TCON_AUTORELOAD4(chan)) > > > > What do you think? > > I don't get the arithmetic here and the code is poor in comment. A nice > comment would valuable here.
Each channel occupies 4 bits in TCON register, but there is a gap of 4 bits after channel 0. In addition for channel 4 the location of autoreload bit in its set of bits is 2 as opposed to 3 for other channels. Here's the layout of the register, for reference: Timer 4 Auto Reload on/off [22] Timer 4 Manual Update [21] Timer 4 Start/Stop [20] Timer 3 Auto Reload on/off [19] Reserved [18] Timer 3 Manual Update [17] Timer 3 Start/Stop [16] Timer 2 Auto Reload on/off [15] Reserved [14] Timer 2 Manual Update [13] Timer 2 Start/Stop [12] Timer 1 Auto Reload on/off [11] Timer 1 Output Inverter on/off [10] Timer 1 Manual Update [9] Timer 1 Start/Stop [8] Reserved [7:5] Dead zone enable/disable [4] Timer 0 Auto Reload on/off [3] Timer 0 Output Inverter on/off [2] Timer 0 Manual Update [1] Timer 0 Start/Stop [0] > May be you can replace 1 << bla by BIT(bla) ? Yes, BIT() would be nice here, but IMHO this is material for separate patch as all the macros in this driver already use 1 << bla. Best regards, Tomasz -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
