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SubjectRe: [PATCH v2 2/3] drm/mediatek: Don't support hdmi connector creation
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Hi,

On 30.03.21 02:08, Laurent Pinchart wrote:
> Hi Dafna,
>
> Thank you for the patch.
>
> On Mon, Mar 29, 2021 at 05:36:31PM +0200, Dafna Hirschfeld wrote:
>> commit f01195148967 ("drm/mediatek: mtk_dpi: Create connector for bridges")
>> broke the display support for elm device since mtk_dpi calls
>> drm_bridge_attach with the flag DRM_BRIDGE_ATTACH_NO_CONNECTOR
>> while mtk_hdmi does not yet support this flag.
>>
>> Fix this by accepting DRM_BRIDGE_ATTACH_NO_CONNECTOR in bridge attachment.
>> Implement the drm_bridge_funcs .detect() and .get_edid() operations, and
>> call drm_bridge_hpd_notify() to report HPD. This provides the
>> necessary API to support disabling connector creation.
>>
>> This patch is inspired by a similar patch for bridge/synopsys/dw-hdmi.c:
>> commit ec971aaa6775 ("drm: bridge: dw-hdmi: Make connector creation optional")
>> But with the difference that in mtk-hdmi only the option of not creating
>> a connector is supported.
>>
>> Fixes: f01195148967 ("drm/mediatek: mtk_dpi: Create connector for bridges")
>> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
>> ---
>> drivers/gpu/drm/mediatek/mtk_hdmi.c | 129 ++++++++++------------------
>> 1 file changed, 44 insertions(+), 85 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
>> index f2c810b767ef..1eeb211b1536 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
>> @@ -186,11 +186,6 @@ static inline struct mtk_hdmi *hdmi_ctx_from_bridge(struct drm_bridge *b)
>> return container_of(b, struct mtk_hdmi, bridge);
>> }
>>
>> -static inline struct mtk_hdmi *hdmi_ctx_from_conn(struct drm_connector *c)
>> -{
>> - return container_of(c, struct mtk_hdmi, conn);
>> -}
>> -
>> static u32 mtk_hdmi_read(struct mtk_hdmi *hdmi, u32 offset)
>> {
>> return readl(hdmi->regs + offset);
>> @@ -1201,48 +1196,30 @@ mtk_hdmi_update_plugged_status(struct mtk_hdmi *hdmi)
>> connector_status_connected : connector_status_disconnected;
>> }
>>
>> -static enum drm_connector_status hdmi_conn_detect(struct drm_connector *conn,
>> - bool force)
>> -{
>> - struct mtk_hdmi *hdmi = hdmi_ctx_from_conn(conn);
>> - return mtk_hdmi_update_plugged_status(hdmi);
>> -}
>> -
>> -static void hdmi_conn_destroy(struct drm_connector *conn)
>> +static struct edid *mtk_hdmi_get_edid(struct mtk_hdmi *hdmi,
>> + struct drm_connector *connector)
>> {
>> - struct mtk_hdmi *hdmi = hdmi_ctx_from_conn(conn);
>> -
>> - mtk_cec_set_hpd_event(hdmi->cec_dev, NULL, NULL);
>> -
>> - drm_connector_cleanup(conn);
>> -}
>> -
>> -static int mtk_hdmi_conn_get_modes(struct drm_connector *conn)
>> -{
>> - struct mtk_hdmi *hdmi = hdmi_ctx_from_conn(conn);
>> struct edid *edid;
>> - int ret;
>>
>> if (!hdmi->ddc_adpt)
>> - return -ENODEV;
>> -
>> - edid = drm_get_edid(conn, hdmi->ddc_adpt);
>> + return NULL;
>> + edid = drm_get_edid(connector, hdmi->ddc_adpt);
>> if (!edid)
>> - return -ENODEV;
>> -
>> + return NULL;
>> hdmi->dvi_mode = !drm_detect_monitor_audio(edid);
>> + return edid;
>> +}
>>
>> - drm_connector_update_edid_property(conn, edid);
>> -
>> - ret = drm_add_edid_modes(conn, edid);
>> - kfree(edid);
>> - return ret;
>> +static enum drm_connector_status mtk_hdmi_detect(struct mtk_hdmi *hdmi)
>> +{
>> + return mtk_hdmi_update_plugged_status(hdmi);
>> }
>>
>> -static int mtk_hdmi_conn_mode_valid(struct drm_connector *conn,
>> - struct drm_display_mode *mode)
>> +static int mtk_hdmi_bridge_mode_valid(struct drm_bridge *bridge,
>> + const struct drm_display_info *info,
>> + const struct drm_display_mode *mode)
>> {
>> - struct mtk_hdmi *hdmi = hdmi_ctx_from_conn(conn);
>> + struct mtk_hdmi *hdmi = hdmi_ctx_from_bridge(bridge);
>> struct drm_bridge *next_bridge;
>>
>> dev_dbg(hdmi->dev, "xres=%d, yres=%d, refresh=%d, intl=%d clock=%d\n",
>> @@ -1267,74 +1244,50 @@ static int mtk_hdmi_conn_mode_valid(struct drm_connector *conn,
>> return drm_mode_validate_size(mode, 0x1fff, 0x1fff);
>> }
>>
>> -static struct drm_encoder *mtk_hdmi_conn_best_enc(struct drm_connector *conn)
>> -{
>> - struct mtk_hdmi *hdmi = hdmi_ctx_from_conn(conn);
>> -
>> - return hdmi->bridge.encoder;
>> -}
>> -
>> -static const struct drm_connector_funcs mtk_hdmi_connector_funcs = {
>> - .detect = hdmi_conn_detect,
>> - .fill_modes = drm_helper_probe_single_connector_modes,
>> - .destroy = hdmi_conn_destroy,
>> - .reset = drm_atomic_helper_connector_reset,
>> - .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>> - .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>> -};
>> -
>> -static const struct drm_connector_helper_funcs
>> - mtk_hdmi_connector_helper_funcs = {
>> - .get_modes = mtk_hdmi_conn_get_modes,
>> - .mode_valid = mtk_hdmi_conn_mode_valid,
>> - .best_encoder = mtk_hdmi_conn_best_enc,
>> -};
>> -
>> static void mtk_hdmi_hpd_event(bool hpd, struct device *dev)
>> {
>> struct mtk_hdmi *hdmi = dev_get_drvdata(dev);
>>
>> - if (hdmi && hdmi->bridge.encoder && hdmi->bridge.encoder->dev)
>> + if (hdmi && hdmi->bridge.encoder && hdmi->bridge.encoder->dev) {
>> + static enum drm_connector_status status;
>> +
>> + status = mtk_hdmi_detect(hdmi);
>> drm_helper_hpd_irq_event(hdmi->bridge.encoder->dev);
>
> I think you can drop this, as drm_bridge_connector_hpd_cb() calls
> drm_kms_helper_hotplug_event().

I see that drm_kms_helper_hotplug_event is called from drm_bridge_connector_hpd_cb,
which is set as a birdge's 'hpd_cb' when calling drm_bridge_connector_enable_hpd,
but mkt_dpi does not call this funcion for the drm_bridge_connector.

I also wonder why bridges have both 'hpd_cb' and a function 'hpd_notify'.
It seems that both are called upon hot-plug event.
It is also confusing that the function drm_bridge_hpd_notify calls the 'hpd_cb'
and not the 'hpd_notfiy'. I can send a patch to change the name to 'drm_bridge_hpd_cb'

Thanks,
Dafna

>
>> + drm_bridge_hpd_notify(&hdmi->bridge, status);
>> + }
>> }
>>
>> /*
>> * Bridge callbacks
>> */
>>
>> +static enum drm_connector_status mtk_hdmi_bridge_detect(struct drm_bridge *bridge)
>> +{
>> + struct mtk_hdmi *hdmi = hdmi_ctx_from_bridge(bridge);
>> +
>> + return mtk_hdmi_detect(hdmi);
>> +}
>> +
>> +static struct edid *mtk_hdmi_bridge_get_edid(struct drm_bridge *bridge,
>> + struct drm_connector *connector)
>> +{
>> + struct mtk_hdmi *hdmi = hdmi_ctx_from_bridge(bridge);
>> +
>> + return mtk_hdmi_get_edid(hdmi, connector);
>
> As mtk_hdmi_get_edid() is only called here, you could inline it in this
> function. Up to you.
>
>> +}
>> +
>> static int mtk_hdmi_bridge_attach(struct drm_bridge *bridge,
>> enum drm_bridge_attach_flags flags)
>> {
>> struct mtk_hdmi *hdmi = hdmi_ctx_from_bridge(bridge);
>> int ret;
>>
>> - if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) {
>> - DRM_ERROR("Fix bridge driver to make connector optional!");
>> + if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)) {
>> + DRM_ERROR("%s: The flag DRM_BRIDGE_ATTACH_NO_CONNECTOR must be supplied\n",
>> + __func__);
>> return -EINVAL;
>> }
>>
>> - ret = drm_connector_init_with_ddc(bridge->encoder->dev, &hdmi->conn,
>> - &mtk_hdmi_connector_funcs,
>> - DRM_MODE_CONNECTOR_HDMIA,
>> - hdmi->ddc_adpt);
>> - if (ret) {
>> - dev_err(hdmi->dev, "Failed to initialize connector: %d\n", ret);
>> - return ret;
>> - }
>> - drm_connector_helper_add(&hdmi->conn, &mtk_hdmi_connector_helper_funcs);
>> -
>> - hdmi->conn.polled = DRM_CONNECTOR_POLL_HPD;
>> - hdmi->conn.interlace_allowed = true;
>> - hdmi->conn.doublescan_allowed = false;
>> -
>> - ret = drm_connector_attach_encoder(&hdmi->conn,
>> - bridge->encoder);
>> - if (ret) {
>> - dev_err(hdmi->dev,
>> - "Failed to attach connector to encoder: %d\n", ret);
>> - return ret;
>> - }
>> -
>> if (hdmi->next_bridge) {
>> ret = drm_bridge_attach(bridge->encoder, hdmi->next_bridge,
>> bridge, flags);
>> @@ -1444,6 +1397,7 @@ static void mtk_hdmi_bridge_atomic_enable(struct drm_bridge *bridge,
>> }
>>
>> static const struct drm_bridge_funcs mtk_hdmi_bridge_funcs = {
>> + .mode_valid = mtk_hdmi_bridge_mode_valid,
>> .atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
>> .atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
>> .atomic_reset = drm_atomic_helper_bridge_reset,
>> @@ -1454,6 +1408,8 @@ static const struct drm_bridge_funcs mtk_hdmi_bridge_funcs = {
>> .mode_set = mtk_hdmi_bridge_mode_set,
>> .atomic_pre_enable = mtk_hdmi_bridge_atomic_pre_enable,
>> .atomic_enable = mtk_hdmi_bridge_atomic_enable,
>> + .detect = mtk_hdmi_bridge_detect,
>> + .get_edid = mtk_hdmi_bridge_get_edid,
>> };
>>
>> static int mtk_hdmi_dt_parse_pdata(struct mtk_hdmi *hdmi,
>> @@ -1762,6 +1718,9 @@ static int mtk_drm_hdmi_probe(struct platform_device *pdev)
>>
>> hdmi->bridge.funcs = &mtk_hdmi_bridge_funcs;
>> hdmi->bridge.of_node = pdev->dev.of_node;
>> + hdmi->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID
>> + | DRM_BRIDGE_OP_HPD;
>
> Nitpicking, I'd align the | to the =.
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>
>> + hdmi->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
>> drm_bridge_add(&hdmi->bridge);
>>
>> ret = mtk_hdmi_clk_enable_audio(hdmi);
>

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