On 09/21/2018 11:17 PM, Pavel Machek wrote: > On Fri 2018-09-21 22:59:40, Jacek Anaszewski wrote: >> Hi Baolin, >> >> On 09/21/2018 05:31 AM, Baolin Wang wrote: >>> Hi Jacek and Pavel, >>> >>> On 11 September 2018 at 10:47, Baolin Wang <baolin.wang@xxxxxxxxxx> wrote: >>>> This patch adds one new led trigger that LED device can configure >>>> the software or hardware pattern and trigger it. >>>> >>>> Consumers can write 'pattern' file to enable the software pattern >>>> which alters the brightness for the specified duration with one >>>> software timer. >>>> >>>> Moreover consumers can write 'hw_pattern' file to enable the hardware >>>> pattern for some LED controllers which can autonomously control >>>> brightness over time, according to some preprogrammed hardware >>>> patterns. >>>> >>>> Signed-off-by: Raphael Teysseyre <rteysseyre@xxxxxxxxx> >>>> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx> > >>> Do you have any comments for the v12 patch set? Thanks. >> >> We will probably have to remove hw_pattern from ledtrig-pattern >> since we are unable to come up with generic interface for it. >> Unless thread [0] will end up with some brilliant ideas. So far >> we're waiting for Pavel's reply. >> >> [0] https://lkml.org/lkml/2018/9/13/1216 > > To paint a picture: > > brightness > > rise hold lower hold down > ^ XXXXXXXXXXXXXXX > | X XX > | X XX > | X XXXXXXXXXXXXXXXXXXXXXXXXXX > +-------------------------------------------------------> time > > This is what Baolin's hardware can do, right? > > This is also what pattern trigger can do, right? > > So all we need to do is match the two interfaces, so that hw_pattern > returns -EINVAL on patterns hardware can not actually do. > > I believe I described code to do that in [0] above. You said that we should get the same effect by writing the same series of tuples to either pattern or hw_pattern file. Below command consists of four tuples (marked with brackets to highlight), and it will activate breathing mode in Baolin's hw_pattern: "[0 rise_duration] [brightness high_duration] [brightness fall_duration] [0 low_duration]" Now, I can't see how these four tuples could force the software fallback to produce breathing effect you depicted. -- Best regards, Jacek Anaszewski
