Re: [PATCH v4 4/8] drm/mediatek: add support for Mediatek SoC MT2701

[Philipp Zabel <p.zabel@pengutronix.de>]

Am Dienstag, den 26.07.2016, 18:42 +0800 schrieb YT Shen:
> Hi CK,
> 
> On Wed, 2016-07-20 at 14:53 +0800, CK Hu wrote:
> > Hi, YT:
> > 
> > Some comments inline.
> > 
> > On Fri, 2016-07-15 at 18:07 +0800, YT Shen wrote:
> > > This patch add support for the Mediatek MT2701 DISP subsystem.
> > > There is only one OVL engine in MT2701.
> > > 
> > > Signed-off-by: YT Shen <yt.shen@mediatek.com>
> > > ---
> > >  drivers/gpu/drm/mediatek/mtk_disp_ovl.c     |    6 ++++
> > >  drivers/gpu/drm/mediatek/mtk_disp_rdma.c    |    6 ++++
> > >  drivers/gpu/drm/mediatek/mtk_drm_ddp.c      |   41 +++++++++++++++++++++++++++
> > >  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.c |    7 +++++
> > >  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h |    1 +
> > >  drivers/gpu/drm/mediatek/mtk_drm_drv.c      |   31 ++++++++++++++++++++
> > >  6 files changed, 92 insertions(+)
> > > 
> > 
> > [snip...]
> > 
> > >  
> > >  static const struct of_device_id mtk_ddp_comp_dt_ids[] = {
> > > +	{ .compatible = "mediatek,mt2701-disp-ovl",   .data = (void *)MTK_DISP_OVL },
> > >  	{ .compatible = "mediatek,mt8173-disp-ovl",   .data = (void *)MTK_DISP_OVL },
> > > +	{ .compatible = "mediatek,mt2701-disp-rdma",  .data = (void *)MTK_DISP_RDMA },
> > >  	{ .compatible = "mediatek,mt8173-disp-rdma",  .data = (void *)MTK_DISP_RDMA },
> > > +	{ .compatible = "mediatek,mt2701-disp-wdma",  .data = (void *)MTK_DISP_WDMA },
> > 
> > Is WDMA different from MT8173 to MT2701. If they are the same, you need
> > not to add compatible of 'mediatek,mt2701-disp-wdma' because use
> > 'mediatek,mt8173-disp-wdma' is enough.
> Yes, the hardware has differences, so we need add new compatible
> 'mt2701-disp-wdma'

It would be nice if you could add a short paragraph to the patch
description about what the hardware differences are (probably just
changed register layout in most cases).

regards
Philipp