[PATCH] clk: qcom: mmcc8974: add frequency table for gfx3d

[PATCH] clk: qcom: mmcc8974: add frequency table for gfx3d

[Brian Masney]

From: Jonathan Marek <jonathan@marek.ca>

Add frequency table for the gfx3d clock that's needed in order to
support the GPU upstream on msm8974-based systems.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Brian Masney <masneyb@onstation.org>
---
 drivers/clk/qcom/mmcc-msm8974.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/clk/qcom/mmcc-msm8974.c b/drivers/clk/qcom/mmcc-msm8974.c
index bcb0a397ef91..e70abfe2a792 100644
--- a/drivers/clk/qcom/mmcc-msm8974.c
+++ b/drivers/clk/qcom/mmcc-msm8974.c
@@ -452,10 +452,17 @@ static struct clk_rcg2 mdp_clk_src = {
 	},
 };
 
+static struct freq_tbl ftbl_gfx3d_clk_src[] = {
+	F(37500000, P_GPLL0, 16, 0, 0),
+	F(533000000, P_MMPLL0, 1.5, 0, 0),
+	{ }
+};
+
 static struct clk_rcg2 gfx3d_clk_src = {
 	.cmd_rcgr = 0x4000,
 	.hid_width = 5,
 	.parent_map = mmcc_xo_mmpll0_1_2_gpll0_map,
+	.freq_tbl = ftbl_gfx3d_clk_src,
 	.clkr.hw.init = &(struct clk_init_data){
 		.name = "gfx3d_clk_src",
 		.parent_names = mmcc_xo_mmpll0_1_2_gpll0,
-- 
2.21.0

Re: [PATCH] clk: qcom: mmcc8974: add frequency table for gfx3d

[Stephen Boyd]

Quoting Brian Masney (2019-10-05 18:01:00)
> From: Jonathan Marek <jonathan@marek.ca>
> 
> Add frequency table for the gfx3d clock that's needed in order to
> support the GPU upstream on msm8974-based systems.
> 
> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> Signed-off-by: Brian Masney <masneyb@onstation.org>
> ---
>  drivers/clk/qcom/mmcc-msm8974.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/clk/qcom/mmcc-msm8974.c b/drivers/clk/qcom/mmcc-msm8974.c
> index bcb0a397ef91..e70abfe2a792 100644
> --- a/drivers/clk/qcom/mmcc-msm8974.c
> +++ b/drivers/clk/qcom/mmcc-msm8974.c
> @@ -452,10 +452,17 @@ static struct clk_rcg2 mdp_clk_src = {
>         },
>  };
>  
> +static struct freq_tbl ftbl_gfx3d_clk_src[] = {
> +       F(37500000, P_GPLL0, 16, 0, 0),
> +       F(533000000, P_MMPLL0, 1.5, 0, 0),
> +       { }
> +};

On msm-3.10 kernel the gpu clk seems to be controlled by the RPM[1].
What is going on here? This code just looks wrong, but I think it was
added as an rcg so that the branch wasn't orphaned and would have some
sane frequency. Eventually we planned to parent it to a clk exposed in
the RPM clk driver. It's been a while so I'm having a hard time
remembering, but I think GPU clk on this device needed to be controlled
by RPM so that DDR self refresh wouldn't interact badly with ocmem? Or
maybe ocmem needed GPU to be enabled to work? Maybe there is some
information in the 3.10 downstream kernel.

> +
>  static struct clk_rcg2 gfx3d_clk_src = {
>         .cmd_rcgr = 0x4000,
>         .hid_width = 5,
>         .parent_map = mmcc_xo_mmpll0_1_2_gpll0_map,
> +       .freq_tbl = ftbl_gfx3d_clk_src,
>         .clkr.hw.init = &(struct clk_init_data){
>                 .name = "gfx3d_clk_src",
>                 .parent_names = mmcc_xo_mmpll0_1_2_gpll0,

[1] https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/arch/arm/mach-msm/clock-rpm-8974.c?h=msm-3.10#n82

Re: [PATCH] clk: qcom: mmcc8974: add frequency table for gfx3d

[Brian Masney]

Hi Stephen,

On Thu, Oct 17, 2019 at 11:13:29AM -0700, Stephen Boyd wrote:
> Quoting Brian Masney (2019-10-05 18:01:00)
> > From: Jonathan Marek <jonathan@marek.ca>
> > 
> > Add frequency table for the gfx3d clock that's needed in order to
> > support the GPU upstream on msm8974-based systems.
> > 
> > Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> > Signed-off-by: Brian Masney <masneyb@onstation.org>
> > ---
> >  drivers/clk/qcom/mmcc-msm8974.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/drivers/clk/qcom/mmcc-msm8974.c b/drivers/clk/qcom/mmcc-msm8974.c
> > index bcb0a397ef91..e70abfe2a792 100644
> > --- a/drivers/clk/qcom/mmcc-msm8974.c
> > +++ b/drivers/clk/qcom/mmcc-msm8974.c
> > @@ -452,10 +452,17 @@ static struct clk_rcg2 mdp_clk_src = {
> >         },
> >  };
> >  
> > +static struct freq_tbl ftbl_gfx3d_clk_src[] = {
> > +       F(37500000, P_GPLL0, 16, 0, 0),
> > +       F(533000000, P_MMPLL0, 1.5, 0, 0),
> > +       { }
> > +};
> 
> On msm-3.10 kernel the gpu clk seems to be controlled by the RPM[1].
> What is going on here? This code just looks wrong, but I think it was
> added as an rcg so that the branch wasn't orphaned and would have some
> sane frequency. Eventually we planned to parent it to a clk exposed in
> the RPM clk driver. It's been a while so I'm having a hard time
> remembering, but I think GPU clk on this device needed to be controlled
> by RPM so that DDR self refresh wouldn't interact badly with ocmem? Or
> maybe ocmem needed GPU to be enabled to work? Maybe there is some
> information in the 3.10 downstream kernel.
> 
> [1] https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/arch/arm/mach-msm/clock-rpm-8974.c?h=msm-3.10#n82

I looked in the MSM 3.4 and 3.10 sources and I can't find that gfx3d
clock in the mmss (the downstream name for the mmcc that's upstream). I
even looked through the git history in the 3.10 sources to see if it was
removed at some point.

The gfx3d_clk_src was added to mmcc-msm8974.c upstream at the time the
file was first introduced into the kernel:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d8b212014e69d6b6323773ce6898f224ef4ed0d6
I haven't been able to find anything else so far where that came from.

The GPU works using kmscube and KDE Plasma Mobile with this patch
applied but won't work without it. As for the status of the GPU working
upstream for MSM8974: My OCMEM and interconnect patches are now in
linux-next and are queued for the next merge window. All that's left is
1) iommu support, 2) this patch (or whatever it needs to become), and
3) add the GPU nodes to device tree for this board.

Would you be willing to reconsider accepting this patch since its 8974
specific and is one of the pieces that gets the GPU working upstream?

Thanks,

Brian


> > +
> >  static struct clk_rcg2 gfx3d_clk_src = {
> >         .cmd_rcgr = 0x4000,
> >         .hid_width = 5,
> >         .parent_map = mmcc_xo_mmpll0_1_2_gpll0_map,
> > +       .freq_tbl = ftbl_gfx3d_clk_src,
> >         .clkr.hw.init = &(struct clk_init_data){
> >                 .name = "gfx3d_clk_src",
> >                 .parent_names = mmcc_xo_mmpll0_1_2_gpll0,
> 

Re: [PATCH] clk: qcom: mmcc8974: add frequency table for gfx3d

[Stephen Boyd]

Quoting Brian Masney (2019-11-04 18:50:32)
> Hi Stephen,
> 
> On Thu, Oct 17, 2019 at 11:13:29AM -0700, Stephen Boyd wrote:
> > Quoting Brian Masney (2019-10-05 18:01:00)
> > > From: Jonathan Marek <jonathan@marek.ca>
> > > 
> > > Add frequency table for the gfx3d clock that's needed in order to
> > > support the GPU upstream on msm8974-based systems.
> > > 
> > > Signed-off-by: Jonathan Marek <jonathan@marek.ca>
> > > Signed-off-by: Brian Masney <masneyb@onstation.org>
> > > ---
> > >  drivers/clk/qcom/mmcc-msm8974.c | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > > 
> > > diff --git a/drivers/clk/qcom/mmcc-msm8974.c b/drivers/clk/qcom/mmcc-msm8974.c
> > > index bcb0a397ef91..e70abfe2a792 100644
> > > --- a/drivers/clk/qcom/mmcc-msm8974.c
> > > +++ b/drivers/clk/qcom/mmcc-msm8974.c
> > > @@ -452,10 +452,17 @@ static struct clk_rcg2 mdp_clk_src = {
> > >         },
> > >  };
> > >  
> > > +static struct freq_tbl ftbl_gfx3d_clk_src[] = {
> > > +       F(37500000, P_GPLL0, 16, 0, 0),
> > > +       F(533000000, P_MMPLL0, 1.5, 0, 0),
> > > +       { }
> > > +};
> > 
> > On msm-3.10 kernel the gpu clk seems to be controlled by the RPM[1].
> > What is going on here? This code just looks wrong, but I think it was
> > added as an rcg so that the branch wasn't orphaned and would have some
> > sane frequency. Eventually we planned to parent it to a clk exposed in
> > the RPM clk driver. It's been a while so I'm having a hard time
> > remembering, but I think GPU clk on this device needed to be controlled
> > by RPM so that DDR self refresh wouldn't interact badly with ocmem? Or
> > maybe ocmem needed GPU to be enabled to work? Maybe there is some
> > information in the 3.10 downstream kernel.
> > 
> > [1] https://source.codeaurora.org/quic/la/kernel/msm-3.10/tree/arch/arm/mach-msm/clock-rpm-8974.c?h=msm-3.10#n82
> 
> I looked in the MSM 3.4 and 3.10 sources and I can't find that gfx3d
> clock in the mmss (the downstream name for the mmcc that's upstream). I
> even looked through the git history in the 3.10 sources to see if it was
> removed at some point.
> 
> The gfx3d_clk_src was added to mmcc-msm8974.c upstream at the time the
> file was first introduced into the kernel:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d8b212014e69d6b6323773ce6898f224ef4ed0d6
> I haven't been able to find anything else so far where that came from.

Yes. I did that! :) I think it was to make sure there weren't any orphan
clks in the tree, which is why I left the code in place to read the clk
frequency but not change it by omitting a frequency table.

> 
> The GPU works using kmscube and KDE Plasma Mobile with this patch
> applied but won't work without it. As for the status of the GPU working
> upstream for MSM8974: My OCMEM and interconnect patches are now in
> linux-next and are queued for the next merge window. All that's left is
> 1) iommu support, 2) this patch (or whatever it needs to become), and
> 3) add the GPU nodes to device tree for this board.
> 
> Would you be willing to reconsider accepting this patch since its 8974
> specific and is one of the pieces that gets the GPU working upstream?
> 

No? I don't believe the kernel should be controlling this clk through
direct register read/writes. Instead, the GPU frequency should be
controlled through an RPM clk. See oxili_gfx3d_clk_src in the link you
mention above [1] and how it indirects to gfx3d_clk_src via
RPM_MEM_CLK_TYPE and OXILI_ID. In the end, anything that's parented to
this rcg in mmcc should probably just be parented to the RPM clk
instead.