[ Upstream commit bbdc00a7de24cc90315b1775fb74841373fe12f7 ]
The rk3288 SoC has two PWM implementations available, the "old" implementation and the "new" one. You can switch between the two of them by flipping a bit in the grf.
The "old" implementation is the default at chip power up but isn't the one that's officially supposed to be used. ...and, in fact, the driver that gets selected in Linux using the rk3288 device tree only supports the "new" implementation.
Long ago I tried to get a switch to the right IP block landed in the PWM driver (search for "rk3288: Switch to use the proper PWM IP") but that got rejected. In the mean time the grf has grown a full-fledged driver that already sets other random bits like this. That means we can now get the fix landed.
For those wondering how things could have possibly worked for the last 4.5 years, folks have mostly been relying on the bootloader to set this bit. ...but occasionally folks have pointed back to my old patch series [1] in downstream kernels.
[1] https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1391597.html
Signed-off-by: Douglas Anderson dianders@chromium.org Signed-off-by: Heiko Stuebner heiko@sntech.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/soc/rockchip/grf.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/soc/rockchip/grf.c b/drivers/soc/rockchip/grf.c index 15e71fd6c513..0931ddb0b384 100644 --- a/drivers/soc/rockchip/grf.c +++ b/drivers/soc/rockchip/grf.c @@ -44,9 +44,11 @@ static const struct rockchip_grf_info rk3036_grf __initconst = { };
#define RK3288_GRF_SOC_CON0 0x244 +#define RK3288_GRF_SOC_CON2 0x24c
static const struct rockchip_grf_value rk3288_defaults[] __initconst = { { "jtag switching", RK3288_GRF_SOC_CON0, HIWORD_UPDATE(0, 1, 12) }, + { "pwm select", RK3288_GRF_SOC_CON2, HIWORD_UPDATE(1, 1, 0) }, };
static const struct rockchip_grf_info rk3288_grf __initconst = {