e6431a0c0d
Fixes a8293 failure to raise LNB voltage in PCTV 461e DVB-S2 Stick affecting multiple users over several years as found here: http://www.linuxquestions.org/questions/linux-hardware-18/pctv-dvb-s2-stick-461e-not-feeding-lnb-4175529374/ https://www.linuxtv.org/wiki/index.php/Pinnacle_PCTV_DVB-S2_Stick_(461e) https://github.com/OpenELEC/OpenELEC.tv/issues/3731 Caused by vIN undervoltage lockout (status register bit 7) when raising LNB to 18V. Addressed by using the higher-precision voltages available on the a8293 to gradually increase (slew) the voltage when voltage increases are requested. Adds volt_slew_nanos_per_mv to a8293_platform_data struct for specifying slew rate. If value is <1 or non-sane (>1600), the original no-slew version for a8293_set_voltage is used. Link: https://lore.kernel.org/linux-media/20211231035326.6759-1-cjritola@gmail.com [mchehab: fixed some coding style issues] Signed-off-by: Chuck Ritola <cjritola@gmail.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>