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Date: Wed, 18 Jul 2018 11:05:49 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Sean Wang <sean.wang@...iatek.com>
Cc: matthias.bgg@...nel.org, ulrich.hecht+renesas@...il.com,
ck.hu@...iatek.com, p.zabel@...gutronix.de, airlied@...ux.ie,
robh+dt@...nel.org, mark.rutland@....com, mturquette@...libre.com,
sboyd@...eaurora.org, lee.jones@...aro.org, davem@...emloft.net,
gregkh@...uxfoundation.org, mchehab@...nel.org,
rdunlap@...radead.org, pi-cheng.chen@...aro.org,
linux-clk@...r.kernel.org, linux@...linux.org.uk,
matthias.bgg@...il.com, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org,
Matthias Brugger <mbrugger@...e.com>
Subject: Re: [resend PATCH v4 4/5] drm/mediatek: Add support for mmsys through a pdev
Hi Sean,
On Wednesday, 18 July 2018 05:57:35 EEST Sean Wang wrote:
> On Wed, 2018-07-18 at 00:03 +0200, matthias.bgg@...nel.org wrote:
> > From: Matthias Brugger <mbrugger@...e.com>
> >
> > The MMSYS subsystem includes clocks and drm components.
> > This patch adds an initailization path through a platform device
> > for the clock part, so that both drivers get probed from the same
> > device tree compatible.
>
> Sorry for that I should have a response earlier for the series.
>
> Some points I felt they're not exactly right and should be fixed up
> before we're moving on
>
> Currently, drm driver have a wrong reference to the dt-binding,
> "mediatek,mt2701-mmsys" or "mediatek,mt8173-mmsys", they should be all
> for the subsystem exporting clock and reset line such common resource to
> its sub-devices. Every subsystem has a similar shape. I hope mmsys
> shouldn't be an exception.
>
> DRM device needs to have its own dt-binding show how connections between
> DRM components being made and its node should be put under mmsys node.
>
> In this way, it becomes easy to see how the topology of the subsystem is
> and grows, like a tree "device tree", instead of hiding the details in
> the implementation.
>
> The similar example we already did for audsys on mt2701 and mt7623 as
> below
>
> audsys: clock-controller@...20000 {
>
compatible = "mediatek,mt7623-audsys",
>
"mediatek,mt2701-audsys",
>
"syscon";
>
...
>
>
afe: audio-controller {
>
compatible = "mediatek,mt7623-audio",
>
"mediatek,mt2701-audio";
>
>
...
>
};
> };
This looks very strange to me. I'm not familiar with the hardware
architecture, but a clock controller that includes an audio controller seems
like a very weird design. It's usually the other way around, you have an audio
controller, and it also contains hardware that produces clocks, and possibly
handles miscellaneous audio-related routing tasks. I would thus expect the
reverse in the device tree:
afe: audio-controller@...20000 {
compatible = "mediatek,mt7623-audio",
"mediatek,mt2701-audio";
..
audsys: clock-controller {
compatible = "mediatek,mt7623-audsys",
"mediatek,mt2701-audsys",
"syscon";
...
};
};
And if audsys only exposes clocks, you don't even need a subnode to represent
it, the audio controller itself can be a clock provider.
afe: audio-controller@...20000 {
compatible = "mediatek,mt7623-audio",
"mediatek,mt2701-audio";
#clock-cells = <1>;
..
};
> > Signed-off-by: Matthias Brugger <mbrugger@...e.com>
> > ---
> >
> > drivers/gpu/drm/mediatek/mtk_drm_drv.c | 18 ++++++++++++++++++
> > drivers/gpu/drm/mediatek/mtk_drm_drv.h | 2 ++
> > 2 files changed, 20 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index dd249cf5121e..c946aea722e5
> > 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> > @@ -173,6 +173,7 @@ static const struct mtk_mmsys_driver_data
> > mt2701_mmsys_driver_data = {>
> > .ext_path = mt2701_mtk_ddp_ext,
> > .ext_len =
ARRAY_SIZE(mt2701_mtk_ddp_ext),
> > .shadow_register = true,
> >
> > + .clk_drv_name = "clk-mt2701-mm",
> >
> > };
> >
> > static const struct mtk_mmsys_driver_data mt8173_mmsys_driver_data = {
> >
> > @@ -180,6 +181,7 @@ static const struct mtk_mmsys_driver_data
> > mt8173_mmsys_driver_data = {>
> > .main_len =
ARRAY_SIZE(mt8173_mtk_ddp_main),
> > .ext_path = mt8173_mtk_ddp_ext,
> > .ext_len =
ARRAY_SIZE(mt8173_mtk_ddp_ext),
> >
> > + .clk_drv_name = "clk-mt8173-mm",
> >
> > };
> >
> > static int mtk_drm_kms_init(struct drm_device *drm)
> >
> > @@ -411,6 +413,19 @@ static int mtk_drm_probe(struct platform_device
> > *pdev)
> >
> > if (IS_ERR(private->config_regs))
> >
> >
return PTR_ERR(private->config_regs);
> >
> > + if (private->data->clk_drv_name) {
> > +
private->clk_dev = platform_device_register_data(dev,
> > +
private->data->clk_drv_name, -1,
> > +
NULL, 0);
> > +
> > +
if (IS_ERR(private->clk_dev)) {
> > +
pr_err("failed to register %s platform
device\n",
> > +
private->data->clk_drv_name);
> > +
> > +
return PTR_ERR(private->clk_dev);
> > +
}
> > + }
> > +
> >
> > /* Iterate over sibling DISP
function blocks */
> > for_each_child_of_node(dev->of_node-
>parent, node) {
> >
> >
const struct of_device_id *of_id;
> >
> > @@ -515,6 +530,9 @@ static int mtk_drm_remove(struct platform_device
> > *pdev)
> >
> > for (i = 0; i <
DDP_COMPONENT_ID_MAX; i++)
> >
> >
of_node_put(private->comp_node[i]);
> >
> > + if (private->clk_dev)
> > +
platform_device_unregister(private->clk_dev);
> > +
> >
> > return 0;
> >
> > }
> >
> > diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.h
> > b/drivers/gpu/drm/mediatek/mtk_drm_drv.h index 86cec19193c4..200eee5de419
> > 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.h
> > +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.h
> > @@ -34,11 +34,13 @@ struct mtk_mmsys_driver_data {
> >
> > const enum mtk_ddp_comp_id
*ext_path;
> > unsigned int ext_len;
> > bool shadow_register;
> >
> > + const char *clk_drv_name;
> >
> > };
> >
> > struct mtk_drm_private {
> >
> > struct drm_device *drm;
> > struct device *dma_dev;
> >
> > + struct platform_device *clk_dev;
> >
> > unsigned int num_pipes;
--
Regards,
Laurent Pinchart
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