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Message-ID: <d5416a2f2a655f6574b17597fdc22615fe2fc22a.camel@mediatek.com>
Date: Wed, 15 Jun 2022 10:58:37 +0800
From: CK Hu <ck.hu@...iatek.com>
To: Bo-Chen Chen <rex-bc.chen@...iatek.com>, <chunkuang.hu@...nel.org>,
<p.zabel@...gutronix.de>, <daniel@...ll.ch>, <robh+dt@...nel.org>,
<krzysztof.kozlowski+dt@...aro.org>, <mripard@...nel.org>,
<tzimmermann@...e.de>, <matthias.bgg@...il.com>, <deller@....de>,
<airlied@...ux.ie>
CC: <msp@...libre.com>, <granquet@...libre.com>,
<jitao.shi@...iatek.com>, <wenst@...omium.org>,
<angelogioacchino.delregno@...labora.com>,
<dri-devel@...ts.freedesktop.org>,
<linux-mediatek@...ts.infradead.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-fbdev@...r.kernel.org>,
<Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v11 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort
driver
Hi, Bo-Chen:
On Fri, 2022-06-10 at 18:55 +0800, Bo-Chen Chen wrote:
> From: Markus Schneider-Pargmann <msp@...libre.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@...iatek.com>
>
> Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
> Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
> [Bo-Chen: Cleanup the drivers and modify comments from reviewers]
> Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> ---
[snip]
> +
> +static int mtk_dp_train_flow(struct mtk_dp *mtk_dp, u8
> target_link_rate,
> + u8 target_lane_count)
> +{
> + u8 lane_adjust[2] = {};
> + bool pass_tps1 = false;
> + bool pass_tps2_3 = false;
> + int train_retries;
> + int status_control;
> + int iteration_count;
> + int ret;
> + u8 prev_lane_adjust;
> +
> + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_LINK_BW_SET,
> target_link_rate);
> + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_LANE_COUNT_SET,
> + target_lane_count |
> DP_LANE_COUNT_ENHANCED_FRAME_EN);
> +
> + if (mtk_dp->train_info.sink_ssc)
> + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_DOWNSPREAD_CTRL,
> + DP_SPREAD_AMP_0_5);
> +
> + train_retries = 0;
> + status_control = 0;
> + iteration_count = 1;
> + prev_lane_adjust = 0xFF;
> +
> + mtk_dp_set_lanes(mtk_dp, target_lane_count / 2);
> + ret = mtk_dp_phy_configure(mtk_dp, target_link_rate,
> target_lane_count);
> + if (ret)
> + return -EINVAL;
> +
> + dev_dbg(mtk_dp->dev,
> + "Link train target_link_rate = 0x%x, target_lane_count
> = 0x%x\n",
> + target_link_rate, target_lane_count);
> +
> + do {
> + train_retries++;
> + if (!mtk_dp->train_info.cable_plugged_in ||
> + mtk_dp->train_info.irq_sta.hpd_disconnect) {
In mtk_dp_hpd_isr_handler(), train_info.irq_sta.hpd_disconnect would
finally be set to false, so you need not to check it here. So remove it
here.
> + return -ENODEV;
> + }
> +
> + if (mtk_dp->train_state < MTK_DP_TRAIN_STATE_TRAINING)
> + return -EAGAIN;
> +
> + if (!pass_tps1) {
> + ret = mtk_dp_train_tps_1(mtk_dp,
> target_lane_count,
> + &iteration_count,
> lane_adjust,
> + &status_control,
> + &prev_lane_adjust);
> + if (!ret) {
> + pass_tps1 = true;
> + train_retries = 0;
> + } else if (ret == -EINVAL) {
> + break;
> + }
> + } else {
> + ret = mtk_dp_train_tps_2_3(mtk_dp,
> target_link_rate,
> + target_lane_count,
> + &iteration_count,
> + lane_adjust,
> &status_control,
> + &prev_lane_adjust);
> + if (!ret) {
> + pass_tps2_3 = true;
> + break;
> + } else if (ret == -EINVAL) {
> + break;
> + }
> + }
> +
> + drm_dp_dpcd_read(&mtk_dp->aux,
> DP_ADJUST_REQUEST_LANE0_1,
> + lane_adjust, sizeof(lane_adjust));
> + mtk_dp_train_update_swing_pre(mtk_dp,
> target_lane_count,
> + lane_adjust);
> + } while (train_retries < MTK_DP_TRAIN_RETRY_LIMIT &&
> + iteration_count < MTK_DP_TRAIN_MAX_ITERATIONS);
> +
> + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_TRAINING_PATTERN_SET,
> + DP_TRAINING_PATTERN_DISABLE);
> + ret = mtk_dp_train_set_pattern(mtk_dp, 0);
> + if (ret)
> + return -EINVAL;
> +
> + if (!pass_tps2_3)
> + return -ETIMEDOUT;
> +
> + mtk_dp->train_info.link_rate = target_link_rate;
> + mtk_dp->train_info.lane_count = target_lane_count;
> +
> + mtk_dp_training_set_scramble(mtk_dp, true);
> +
> + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_LANE_COUNT_SET,
> + target_lane_count |
> + DP_LANE_COUNT_ENHANCED_FRAME_EN);
> + mtk_dp_set_enhanced_frame_mode(mtk_dp, true);
> +
> + return ret;
> +}
> +
[snip]
> +
> +/*
> + * We need to handle HPD signal in eDP even though eDP is a always
> connected
> + * device. Besides connected status, there is another feature for
> HPD signal -
> + * HPD pulse: it presents an IRQ from sink devices to source devices
> (Refer to
> + * 5.1.4 of DP1.4 spec).
> + */
> +static irqreturn_t mtk_dp_hpd_isr_handler(struct mtk_dp *mtk_dp)
> +{
> + bool connected;
> + u32 irq_status = mtk_dp_swirq_get_clear(mtk_dp) |
> + mtk_dp_hwirq_get_clear(mtk_dp);
> + struct mtk_dp_train_info *train_info = &mtk_dp->train_info;
> +
> + if (irq_status & MTK_DP_HPD_INTERRUPT)
> + train_info->irq_sta.hpd_inerrupt = true;
> + if (irq_status & MTK_DP_HPD_CONNECT)
> + train_info->irq_sta.hpd_connect = true;
> + if (irq_status & MTK_DP_HPD_DISCONNECT)
> + train_info->irq_sta.hpd_disconnect = true;
> +
train_info->irq_sta.hpd_connect is used only in this function, so let
hpd_connect to be local variable.
> + if (!irq_status)
> + return IRQ_HANDLED;
> +
> + connected = mtk_dp_plug_state(mtk_dp);
> + if (connected || !train_info->cable_plugged_in)
> + train_info->irq_sta.hpd_disconnect = false;
> + else if (!connected || train_info->cable_plugged_in)
> + train_info->irq_sta.hpd_connect = false;
> +
> + if (!(train_info->irq_sta.hpd_connect ||
> + train_info->irq_sta.hpd_disconnect))
> + return IRQ_WAKE_THREAD;
> +
> + if (train_info->irq_sta.hpd_connect) {
> + train_info->irq_sta.hpd_connect = false;
> + train_info->cable_plugged_in = true;
> + } else {
> + train_info->irq_sta.hpd_disconnect = false;
> + train_info->cable_plugged_in = false;
> + mtk_dp->train_state = MTK_DP_TRAIN_STATE_TRAINING;
> + }
> + train_info->cable_state_change = true;
> +
> + return IRQ_WAKE_THREAD;
> +}
> +
[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_sta.hpd_disconnect) {
In mtk_dp_hpd_isr_handler(), train_info.irq_sta.hpd_disconnect would
finally be set to false, so you need not to check it here. So remove it
here.
Regards,
CK
> + ret = -EAGAIN;
> + goto err;
> + }
> +
> + 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);
> + ret = -EINVAL;
> + goto err;
> + }
> +
> + 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;
> + }
> + }
> +err:
> + 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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