From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Thompson Date: Thu, 20 Sep 2018 16:23:49 +0000 Subject: Re: Re: [PATCH] backlight: pwm_bl: Fix brightness levels for non-DT case. Message-Id: <9cc21df6-67f2-e210-33b8-e0e14f052e7e@linaro.org> List-Id: References: <20180824155402.2822-1-enric.balletbo@collabora.com> <87h8ji98jp.fsf@belgarion.home> In-Reply-To: <87h8ji98jp.fsf@belgarion.home> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Robert Jarzmik , Enric Balletbo i Serra Cc: linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, Bartlomiej Zolnierkiewicz , Jingoo Han , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Thierry Reding , kernel@collabora.com, lee.jones@linaro.org On 25/08/18 01:04, Robert Jarzmik wrote: > Enric Balletbo i Serra writes: > >> Commit '88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED >> linearly to human eye")' allows the possibility to compute a default >> brightness table when there isn't the brightness-levels property in the >> DT. Unfortunately the changes made broke the pwm backlight for the >> non-DT boards. >> >> Usually, the non-DT boards don't pass the brightness levels via platform >> data, instead, they set the max_brightness in their platform data and the >> driver calculates the level without a table. The ofending patch assumed >> that when there is no brightness levels table we should create one, but this >> is clearly wrong for the non-DT case. >> >> After this patch the code handles the DT and the non-DT case taking in >> consideration also if max_brightness is set or not. The default table is >> only created when neither, brightness-levels and max_brightness, are >> set. >> >> The patch also fixes another issue found by Robert. Before this patch >> looks like a division by 0 was possible when state.period returned 0 by >> pwm_get_state(). This is because pwm_get_state() was called before >> pwm_apply_args() so state.period was not initialized. The patch moves >> the pwm_apply_args() call before any call to pwm_get_state(). >> >> Fixes: '88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")' >> Reported-by: Robert Jarzmik >> Signed-off-by: Enric Balletbo i Serra > Tested-by: Robert Jarzmik Acked-by: Daniel Thompson (and sorry for the delay) Daniel.