Re: [RFC PATCH 2/5] drm/mediatek: dpi: Add dpintf support

[Markus Schneider-Pargmann <msp@baylibre.com>]

Hi,

On Tue, Aug 17, 2021 at 05:50:44PM +0800, CK Hu wrote:
> Hi, Markus:
> 
> On Mon, 2021-08-16 at 21:25 +0200, Markus Schneider-Pargmann wrote:
> > dpintf is the displayport interface hardware unit. This unit is similar
> > to dpi and can reuse most of the code.
> > 
> > This patch adds support for mt8195-dpintf to this dpi driver. Main
> > differences are:
> >  - Some features/functional components are not available for dpintf
> >    which are now excluded from code execution once is_dpintf is set
> >  - dpintf can and needs to choose between different clockdividers based
> >    on the clockspeed. This is done by choosing a different clock parent.
> >  - There are two additional clocks that need to be managed. These are
> >    only set for dpintf and will be set to NULL if not supplied. The
> >    clk_* calls handle these as normal clocks then.
> >  - Some register contents differ slightly between the two components. To
> >    work around this I added register bits/masks with a DPINTF_ prefix
> >    and use them where different.
> > 
> > Based on a separate driver for dpintf created by
> > Jason-JH.Lin <jason-jh.lin@mediatek.com>.
> > 
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> > ---
> >  drivers/gpu/drm/mediatek/mtk_dpi.c      | 282 ++++++++++++++++++++----
> >  drivers/gpu/drm/mediatek/mtk_dpi_regs.h |  12 +
> >  2 files changed, 247 insertions(+), 47 deletions(-)
> > 
> 
> [snip]
> 
> >  
> > +static void mtk_dpi_set_pixel_clk_parent(struct mtk_dpi *dpi,
> > +					 unsigned int factor)
> > +{
> > +	struct clk *new_parent;
> > +
> > +	switch (factor) {
> > +	case 16:
> > +		new_parent = dpi->tvd_clks[MTK_DPI_TVDPLL_D16].clk;
> > +		break;
> > +	case 8:
> > +		new_parent = dpi->tvd_clks[MTK_DPI_TVDPLL_D8].clk;
> > +		break;
> > +	case 4:
> > +		new_parent = dpi->tvd_clks[MTK_DPI_TVDPLL_D4].clk;
> > +		break;
> > +	case 2:
> > +		new_parent = dpi->tvd_clks[MTK_DPI_TVDPLL_D2].clk;
> > +		break;
> > +	default:
> > +		new_parent = NULL;
> > +	}
> > +	if (new_parent)
> > +		clk_set_parent(dpi->pixel_clk, new_parent);
> 
> I prefer that dpi->pixel_clk provide set_rate() interface, and let clock
> driver to control the parent of dpi->pixel_clk.

Good point, will do that, thanks.

Best,
Markus

> 
> Regards,
> CK
> 
> > +}
> > +
> >  static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
> >  				    struct drm_display_mode *mode)
> >  {
> > @@ -465,6 +568,8 @@ static int mtk_dpi_set_display_mode(struct mtk_dpi *dpi,
> >  	drm_display_mode_to_videomode(mode, &vm);
> >  	pll_rate = vm.pixelclock * factor;
> >  
> > +	mtk_dpi_set_pixel_clk_parent(dpi, factor);
> > +
> >  	dev_dbg(dpi->dev, "Want PLL %lu Hz, pixel clock %lu Hz\n",
> >  		pll_rate, vm.pixelclock);
> >  
> 
> 

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