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SubjectRe: [PATCH v10 18/21] drm/mediatek: Add mt8195 Embedded DisplayPort driver
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On Tue, 2022-06-07 at 15:30 +0800, CK Hu wrote:
> Hi, Rex:
>
> On Mon, 2022-05-23 at 12:47 +0200, Guillaume Ranquet wrote:
> > From: Markus Schneider-Pargmann <msp@baylibre.com>
> >
> > This patch adds a 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
> > Jason-JH.Lin <jason-jh.lin@mediatek.com>.
> >
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > ---
>
> [snip]
>
> > +
> > +static ssize_t mtk_dp_aux_transfer(struct drm_dp_aux *mtk_aux,
> > + struct drm_dp_aux_msg *msg)
> > +{
> > + struct mtk_dp *mtk_dp;
> > + bool is_read;
> > + u8 request;
> > + size_t accessed_bytes = 0;
> > + int ret = 0;
> > +
> > + mtk_dp = container_of(mtk_aux, struct mtk_dp, aux);
> > +
> > + if (!mtk_dp->train_info.cable_plugged_in ||
> > + mtk_dp->train_info.irq_status & MTK_DP_HPD_DISCONNECT) {
> > + mtk_dp->train_state = MTK_DP_TRAIN_STATE_CHECKCAP;
>
> Changing state here has no any effect, so drop this.
>

ok, I will drop it.

> > + return -EAGAIN;
> > + }
> > +
> > + switch (msg->request) {
> > + case DP_AUX_I2C_MOT:
> > + case DP_AUX_I2C_WRITE:
> > + case DP_AUX_NATIVE_WRITE:
> > + case DP_AUX_I2C_WRITE_STATUS_UPDATE:
> > + case DP_AUX_I2C_WRITE_STATUS_UPDATE | DP_AUX_I2C_MOT:
> > + request = msg->request &
> > ~DP_AUX_I2C_WRITE_STATUS_UPDATE;
> > + is_read = false;
> > + break;
> > + case DP_AUX_I2C_READ:
> > + case DP_AUX_NATIVE_READ:
> > + case DP_AUX_I2C_READ | DP_AUX_I2C_MOT:
> > + request = msg->request;
> > + is_read = true;
> > + break;
> > + default:
> > + drm_err(mtk_aux->drm_dev, "invalid aux cmd = %d\n",
> > + msg->request);
> > + return -EINVAL;
> > + }
> > +
> > + if (msg->size == 0) {
> > + ret = mtk_dp_aux_do_transfer(mtk_dp, is_read, request,
> > + msg->address +
> > accessed_bytes,
> > + msg->buffer +
> > accessed_bytes, 0);
> > + } else {
> > + while (accessed_bytes < msg->size) {
> > + size_t to_access =
> > + min_t(size_t, DP_AUX_MAX_PAYLOAD_BYTES,
> > + msg->size - accessed_bytes);
> > +
> > + ret = mtk_dp_aux_do_transfer(mtk_dp,
> > + is_read, request,
> > + msg->address +
> > accessed_bytes,
> > + msg->buffer +
> > accessed_bytes,
> > + to_access);
> > +
> > + if (ret) {
> > + drm_info(mtk_dp->drm_dev,
> > + "Failed to do AUX transfer:
> > %d\n", ret);
> > + break;
> > + }
> > + accessed_bytes += to_access;
> > + }
> > + }
> > +
> > + if (ret) {
> > + msg->reply = DP_AUX_NATIVE_REPLY_NACK |
> > DP_AUX_I2C_REPLY_NACK;
> > + return ret;
> > + }
> > +
> > + msg->reply = DP_AUX_NATIVE_REPLY_ACK | DP_AUX_I2C_REPLY_ACK;
> > + return msg->size;
> > +}
>
>

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