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clk: qcom: Add a dummy enable function for GX gdsc

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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: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
This commit is contained in:
Jordan Crouse 2018-11-26 10:20:32 -07:00 committed by Stephen Boyd
parent 7895861a96
commit 85a3d920d3
1 changed files with 26 additions and 0 deletions
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26
drivers/clk/qcom/gpucc-sdm845.c
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@ -131,11 +131,37 @@ static struct gdsc gpu_cx_gdsc = {
.flags = VOTABLE,
};
/*
* On SDM845 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 gpu_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 | AON_RESET | POLL_CFG_GDSCR,