Re: [PATCH 2/3] clk: qcom: Add support for GXCLK for Milos

[Jagadeesh Kona <jagadeesh.kona@oss.qualcomm.com>]

On 3/31/2026 8:07 AM, Alexander Koskovich wrote:
> On Friday, March 6th, 2026 at 8:56 AM, Luca Weiss <luca.weiss@fairphone.com> wrote:
> 
>> GXCLKCTL (Graphics GX Clock Controller) is a block dedicated to managing
>> clocks for the GPU subsystem on GX power domain. The GX clock controller
>> driver manages only the GX GDSC and the rest of the resources of the
>> controller are managed by the firmware.
>>
>> We can use the existing kaanapali driver for Milos as well since the
>> GX_CLKCTL_GX_GDSC supported by the Linux driver requires the same
>> configuration.
>>
>> Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
>> ---
>>  drivers/clk/qcom/Makefile             | 2 +-
>>  drivers/clk/qcom/gxclkctl-kaanapali.c | 1 +
>>  2 files changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
>> index 90ea21c3b7cf..155830140d26 100644
>> --- a/drivers/clk/qcom/Makefile
>> +++ b/drivers/clk/qcom/Makefile
>> @@ -182,7 +182,7 @@ obj-$(CONFIG_SM_GPUCC_8350) += gpucc-sm8350.o
>>  obj-$(CONFIG_SM_GPUCC_8450) += gpucc-sm8450.o
>>  obj-$(CONFIG_SM_GPUCC_8550) += gpucc-sm8550.o
>>  obj-$(CONFIG_SM_GPUCC_8650) += gpucc-sm8650.o
>> -obj-$(CONFIG_SM_GPUCC_MILOS) += gpucc-milos.o
>> +obj-$(CONFIG_SM_GPUCC_MILOS) += gpucc-milos.o gxclkctl-kaanapali.o
>>  obj-$(CONFIG_SM_LPASSCC_6115) += lpasscc-sm6115.o
>>  obj-$(CONFIG_SM_TCSRCC_8550) += tcsrcc-sm8550.o
>>  obj-$(CONFIG_SM_TCSRCC_8650) += tcsrcc-sm8650.o
>> diff --git a/drivers/clk/qcom/gxclkctl-kaanapali.c b/drivers/clk/qcom/gxclkctl-kaanapali.c
>> index 3ee512f34967..d3899420d6f2 100644
>> --- a/drivers/clk/qcom/gxclkctl-kaanapali.c
>> +++ b/drivers/clk/qcom/gxclkctl-kaanapali.c
>> @@ -54,6 +54,7 @@ static const struct qcom_cc_desc gx_clkctl_kaanapali_desc = {
>>  static const struct of_device_id gx_clkctl_kaanapali_match_table[] = {
>>  	{ .compatible = "qcom,glymur-gxclkctl" },
>>  	{ .compatible = "qcom,kaanapali-gxclkctl" },
>> +	{ .compatible = "qcom,milos-gxclkctl" },
>>  	{ }
>>  };
>>  MODULE_DEVICE_TABLE(of, gx_clkctl_kaanapali_match_table);
>>
>> --
>> 2.53.0
>>
> 
> Was running into gx_clkctl_gx_gdsc being stuck on when GPU was doing runtime pm
> and it seems like this GDSC requires GPU_CC_GX_AHB_FF_CLK to be enabled. Though
> it is already in gpu_cc_milos_critical_cbcrs, the GMU firmware appears to be
> disabling it.
> 
> Relevant downstream change:
> https://git.codelinaro.org/clo/la/kernel/qcom/-/commit/3c1f31518edb7b094b9b9285287ba49a5c9196d8
> 

Hi Alexander,

This change was introduced as a temporary placeholder specific to downstream GPU SW & GPUCC code,
to unblock the gx gdsc warnings observed during system resume. But it is not the final
implementation and change was reverted later in below commit:
https://git.codelinaro.org/clo/la/kernel/qcom/-/commit/11bd8d8d6f654cf156bb4fbbfe6587e0c41adc2b
 
But you are right, gpu_cc_gx_ahb_ff_clk is indeed required for GX GDSC register access. And the
actual requirement is linux GMU driver should disable the GX GDSC only in GMU recovery use case
at which point the necessary clock will already be enabled by firmware. In all other cases, the
GX GDSC should never be enabled/disabled from linux.
 
In the upstream implementation of GMU driver, the GX GDSC is being enabled/disabled in every runtime
resume/suspend of GMU driver which is leading to these GX GDSC warnings.  Milos GPU architecture is
similar to that of Pakala and similar GX GDSC warnings were reported on Pakala already[1].
Discussions are in progress with internal GPU SW team to see if GX GDSC can be handled gracefully
only during GMU recovery use case and not control it in other scenarios, to avoid this issue and
without impacting any other GPU use cases.
 
[1]: https://lore.kernel.org/all/CAH2e8h4R-nF+eV+OnkSySKSY5_H-V8Ndyfhac3=VNQ-bMaBeFg@mail.gmail.com/

Thanks,
Jagadeesh

>>
>>
>