Re: [PATCH v14 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver

Rex-BC Chen
2022-07-14T08:52:47Z

On Wed, 2022-07-13 at 17:31 +0800, CK Hu wrote:
> Hi, Bo-Chen:
>
> On Tue, 2022-07-12 at 19:12 +0800, Bo-Chen Chen wrote:
> > From: Markus Schneider-Pargmann <msp@baylibre.com>
> >
> > This patch adds a embedded displayport driver for the MediaTek
> > mt8195
> > SoC.
> >
> > It supports the MT8195, the embedded DisplayPort units. It offers
> > DisplayPort 1.4 with up to 4 lanes.
> >
> > The driver creates a child device for the phy. The child device
> > will
> > never exist without the parent being active. As they are sharing a
> > register range, the parent passes a regmap pointer to the child so
> > that
> > both can work with the same register range. The phy driver sets
> > device
> > data that is read by the parent to get the phy device that can be
> > used
> > to control the phy properties.
> >
> > This driver is based on an initial version by
> > Jitao shi <jitao.shi@mediatek.com>
> >
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
> > ---
>
> [snip]
>
> > +
> > +static void mtk_dp_bulk_16bit_write(struct mtk_dp *mtk_dp, u32
> > offset, u8 *buf,
> > + size_t length)
>
> The offset would always be MTK_DP_AUX_P0_3708, so drop offset and use
> MTK_DP_AUX_P0_3708 directly.
>

Hello CK,

I don't think it's a good idea. this function is a fucntion of writing
registers. I want to keep the offset variable.

> > +{
> > + int i;
> > + int num_regs = (length + 1) / 2;
> > +
> > + /* 2 bytes per register */
> > + for (i = 0; i < num_regs; i++) {
> > + u32 val = buf[i * 2] |
> > + (i * 2 + 1 < length ? buf[i * 2 + 1] << 8 :
> > 0);
> > +
> > + if (mtk_dp_write(mtk_dp, offset + i * 4, val))
> > + return;
> > + }
>
> for (i = 0; i < length; i += 2) {
> val = buf[i] | (i + 1 < length ? buf[i + 1] << 8 : 0);
> if (mtk_dp_write(mtk_dp, MTK_DP_AUX_P0_3708 + i * 2, val))
> return;
> }
>

ok.

BRs,
Bo-Chen

> Regards,
> CK
>
> > +}
> > +
>
>