From: Taniya Das tdas@codeaurora.org
Most of the time the CPU should not be touching the GX domain on the GPU except for a very special use case when the CPU needs to force the GX headswitch off. Add a dummy enable function for the GX gdsc to simulate success so that the pm_runtime reference counting is correct.
Signed-off-by: Taniya Das tdas@codeaurora.org --- drivers/clk/qcom/gpucc-sc7180.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+)
diff --git a/drivers/clk/qcom/gpucc-sc7180.c b/drivers/clk/qcom/gpucc-sc7180.c index ec61194..3b29f19 100644 --- a/drivers/clk/qcom/gpucc-sc7180.c +++ b/drivers/clk/qcom/gpucc-sc7180.c @@ -172,8 +172,45 @@ enum { .flags = VOTABLE, };
+/* + * On SC7180 the GPU GX domain is *almost* entirely controlled by the GMU + * running in the CX domain so the CPU doesn't need to know anything about the + * GX domain EXCEPT.... + * + * Hardware constraints dictate that the GX be powered down before the CX. If + * the GMU crashes it could leave the GX on. In order to successfully bring back + * the device the CPU needs to disable the GX headswitch. There being no sane + * way to reach in and touch that register from deep inside the GPU driver we + * need to set up the infrastructure to be able to ensure that the GPU can + * ensure that the GX is off during this super special case. We do this by + * defining a GX gdsc with a dummy enable function and a "default" disable + * function. + * + * This allows us to attach with genpd_dev_pm_attach_by_name() in the GPU + * driver. During power up, nothing will happen from the CPU (and the GMU will + * power up normally but during power down this will ensure that the GX domain + * is *really* off - this gives us a semi standard way of doing what we need. + */ +static int gx_gdsc_enable(struct generic_pm_domain *domain) +{ + /* Do nothing but give genpd the impression that we were successful */ + return 0; +} + +static struct gdsc gx_gdsc = { + .gdscr = 0x100c, + .clamp_io_ctrl = 0x1508, + .pd = { + .name = "gpu_gx_gdsc", + .power_on = gx_gdsc_enable, + }, + .pwrsts = PWRSTS_OFF_ON, + .flags = CLAMP_IO, +}; + static struct gdsc *gpu_cc_sc7180_gdscs[] = { [CX_GDSC] = &cx_gdsc, + [GX_GDSC] = &gx_gdsc, };
static struct clk_regmap *gpu_cc_sc7180_clocks[] = {