[Freedreno] [RFC 2/6] drm/msm/dpu: support setting up two independent DSI connectors
Dmitry Baryshkov
dmitry.baryshkov at linaro.org
Fri Jul 2 09:20:14 UTC 2021
On 02/07/2021 00:12, abhinavk at codeaurora.org wrote:
> On 2021-06-09 14:17, Dmitry Baryshkov wrote:
>> Move setting up encoders from set_encoder_mode to
>> _dpu_kms_initialize_dsi() / _dpu_kms_initialize_displayport(). This
>> allows us to support not only "single DSI" and "dual DSI" but also "two
>> independent DSI" configurations. In future this would also help adding
>> support for multiple DP connectors.
>>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> I will have to see Bjorn's changes to check why it was dependent on this
> cleanup.
> Is the plan to call _dpu_kms_initialize_displayport() twice?
Yes. He needs to initialize several displayport interfaces. With the
current code he has to map ids in the set_encoder_mode, using encoder
ids (to fill up the info.h_tile_instance, which is hardcoded to 0 for DP
in the current code).
> But still I am not able to put together where is the dependency on that
> series
> with this one. Can you please elaborate on that a little bit?
It is possible to support independent outputs with the current code. I
did that for DSI, Bjorn did for DP. However it results in quite an ugly
code to map received encoder in set_encoder_mode back to the DSI (DP)
instances to fill the h_tiles. If we drop the whole set_encoder_mode
story and call dpu_encoder_setup right from the
_dpu_kms_initialize_dsi() (or _dpu_kms_initialize_displayport()),
supporting multiple outputs becomes an easy task.
>
>> ---
>> drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 89 ++++++++++++-------------
>> 1 file changed, 44 insertions(+), 45 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> index 1d3a4f395e74..b63e1c948ff2 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> @@ -471,30 +471,55 @@ static int _dpu_kms_initialize_dsi(struct
>> drm_device *dev,
>> struct dpu_kms *dpu_kms)
>> {
>> struct drm_encoder *encoder = NULL;
>> + struct msm_display_info info;
>> int i, rc = 0;
>>
>> if (!(priv->dsi[0] || priv->dsi[1]))
>> return rc;
>>
>> - /*TODO: Support two independent DSI connectors */
>> - encoder = dpu_encoder_init(dev, DRM_MODE_ENCODER_DSI);
>> - if (IS_ERR(encoder)) {
>> - DPU_ERROR("encoder init failed for dsi display\n");
>> - return PTR_ERR(encoder);
>> - }
>> -
>> - priv->encoders[priv->num_encoders++] = encoder;
>> -
>> for (i = 0; i < ARRAY_SIZE(priv->dsi); i++) {
>> if (!priv->dsi[i])
>> continue;
>>
>> + if (!encoder) {
>> + encoder = dpu_encoder_init(dev, DRM_MODE_ENCODER_DSI);
>> + if (IS_ERR(encoder)) {
>> + DPU_ERROR("encoder init failed for dsi display\n");
>> + return PTR_ERR(encoder);
>> + }
>> +
>> + priv->encoders[priv->num_encoders++] = encoder;
>> +
>> + memset(&info, 0, sizeof(info));
>> + info.intf_type = encoder->encoder_type;
>> + info.capabilities = msm_dsi_is_cmd_mode(priv->dsi[i]) ?
>> + MSM_DISPLAY_CAP_CMD_MODE :
>> + MSM_DISPLAY_CAP_VID_MODE;
>> + }
>> +
>> rc = msm_dsi_modeset_init(priv->dsi[i], dev, encoder);
>> if (rc) {
>> DPU_ERROR("modeset_init failed for dsi[%d], rc = %d\n",
>> i, rc);
>> break;
>> }
>> +
>> + info.h_tile_instance[info.num_of_h_tiles++] = i;
>> +
>> + if (!msm_dsi_is_dual_dsi(priv->dsi[i])) {
>
> I would like to clarify the terminology of dual_dsi in the current DSI
> driver before the rest of the reviews.
> Today IS_DUAL_DSI() means that two DSIs are driving the same display and
> the two DSIs are operating in master-slave mode
> and are being driven by the same PLL.
Yes
> Usually, dual independent DSI means two DSIs driving two separate panels
> using two separate PLLs ( DSI0 with PLL0 and DSI1 with PLL1)
Let's stop calling it 'dual'. I'd suggest to continue using what was
there in the source file: 'two independent DSI'.
> I assume thats happening due to the foll logic and both DSI PHYs are
> operating in STANDALONE mode:
>
> if (!IS_DUAL_DSI()) {
> ret = msm_dsi_host_register(msm_dsi->host, true);
> if (ret)
> return ret;
>
> msm_dsi_phy_set_usecase(msm_dsi->phy, MSM_DSI_PHY_STANDALONE);
> ret = msm_dsi_host_set_src_pll(msm_dsi->host, msm_dsi->phy);
Yes. If we have two independent DSI outputs, we'd like them to work in
STANDALONE mode.
>> + rc = dpu_encoder_setup(dev, encoder, &info);
>> + if (rc)
>> + DPU_ERROR("failed to setup DPU encoder %d: rc:%d\n",
>> + encoder->base.id, rc);
>> + encoder = NULL;
>> + }
>> + }
>> +
>> + if (encoder) {
>
> We will hit this case only for split-DSI right? ( that is two DSIs
> driving the same panel ).
Yes, only in this case.
> Even single DSI will be created in the above loop now. So this looks a
> bit confusing at the moment.
What is so confusing? I can probably add a comment there. If the encoder
drivers single DSI output, we setup it after creating the DSI. If the
encoder drives dual DSI outpu, we have to setup it after creating both
DSI outputs.
I have tried calling dpu_encoder_setup from a separate if/loop
condition, but it resulted in even uglier code.
> I think we need to be more clear on dual-DSI Vs split-DSI to avoid
> confusion in the code about which one means what and the one
> which we are currently using. So what about having IS_DUAL_DSI() and
> IS_SPLIT_DSI() to distinguish the terminologies and chaging
> DSI driver accordingly.
The word 'SPLIT' is already overloaded in my opinion. I'd prefer to keep
on using 'dual DSI' for the master/slave case and not to use 'dual' for
just two standalone DSI interfaces.
>
>> + rc = dpu_encoder_setup(dev, encoder, &info);
>> + if (rc)
>> + DPU_ERROR("failed to setup DPU encoder %d: rc:%d\n",
>> + encoder->base.id, rc);
>> }
>>
>> return rc;
>> @@ -505,6 +530,7 @@ static int _dpu_kms_initialize_displayport(struct
>> drm_device *dev,
>> struct dpu_kms *dpu_kms)
>> {
>> struct drm_encoder *encoder = NULL;
>> + struct msm_display_info info;
>> int rc = 0;
>>
>> if (!priv->dp)
>> @@ -516,6 +542,7 @@ static int _dpu_kms_initialize_displayport(struct
>> drm_device *dev,
>> return PTR_ERR(encoder);
>> }
>>
>> + memset(&info, 0, sizeof(info));
>> rc = msm_dp_modeset_init(priv->dp, dev, encoder);
>> if (rc) {
>> DPU_ERROR("modeset_init failed for DP, rc = %d\n", rc);
>> @@ -524,6 +551,14 @@ static int _dpu_kms_initialize_displayport(struct
>> drm_device *dev,
>> }
>>
>> priv->encoders[priv->num_encoders++] = encoder;
>> +
>> + info.num_of_h_tiles = 1;
>> + info.capabilities = MSM_DISPLAY_CAP_VID_MODE;
>> + info.intf_type = encoder->encoder_type;
>> + rc = dpu_encoder_setup(dev, encoder, &info);
>> + if (rc)
>> + DPU_ERROR("failed to setup DPU encoder %d: rc:%d\n",
>> + encoder->base.id, rc);
>> return rc;
>> }
>>
>> @@ -726,41 +761,6 @@ static void dpu_kms_destroy(struct msm_kms *kms)
>> msm_kms_destroy(&dpu_kms->base);
>> }
>>
>> -static void _dpu_kms_set_encoder_mode(struct msm_kms *kms,
>> - struct drm_encoder *encoder,
>> - bool cmd_mode)
>> -{
>> - struct msm_display_info info;
>> - struct msm_drm_private *priv = encoder->dev->dev_private;
>> - int i, rc = 0;
>> -
>> - memset(&info, 0, sizeof(info));
>> -
>> - info.intf_type = encoder->encoder_type;
>> - info.capabilities = cmd_mode ? MSM_DISPLAY_CAP_CMD_MODE :
>> - MSM_DISPLAY_CAP_VID_MODE;
>> -
>> - switch (info.intf_type) {
>> - case DRM_MODE_ENCODER_DSI:
>> - /* TODO: No support for DSI swap */
>> - for (i = 0; i < ARRAY_SIZE(priv->dsi); i++) {
>> - if (priv->dsi[i]) {
>> - info.h_tile_instance[info.num_of_h_tiles] = i;
>> - info.num_of_h_tiles++;
>> - }
>> - }
>> - break;
>> - case DRM_MODE_ENCODER_TMDS:
>> - info.num_of_h_tiles = 1;
>> - break;
>> - }
>> -
>> - rc = dpu_encoder_setup(encoder->dev, encoder, &info);
>> - if (rc)
>> - DPU_ERROR("failed to setup DPU encoder %d: rc:%d\n",
>> - encoder->base.id, rc);
>> -}
>> -
> It seems we can get rid of set_encoder_mode for DP because the way we
> are using it today seems not right.
> Ideally, the purpose was that once we read the EDID, the information we
> read like the tile group etc
> can be used when we are setting up the encoder. But today, we are just
> hard-coding the number of tiles.
> But I just think whether looking ahead, we should still have some
> callback which can be called after
> EDID has been read instead of doing it in
> _dpu_kms_initialize_displayport. Perhaps that can be a separate patch.
For the MST support? It is definitely a separate patch. For now we want
to be able to drive a much simpler config: SST on several connected DPs.
>
>> static irqreturn_t dpu_irq(struct msm_kms *kms)
>> {
>> struct dpu_kms *dpu_kms = to_dpu_kms(kms);
>> @@ -863,7 +863,6 @@ static const struct msm_kms_funcs kms_funcs = {
>> .get_format = dpu_get_msm_format,
>> .round_pixclk = dpu_kms_round_pixclk,
>> .destroy = dpu_kms_destroy,
>> - .set_encoder_mode = _dpu_kms_set_encoder_mode,
> I would like to get Rob's comment on why we had set_encoder_mode in the
> first place. Its there even in mdp5.
>
> in current msm dsi, the dsi bind will happen only after the panel has
> attached
> and the msm_drv's bind will happen only after that since its the
> component master
> in that case what was the need for set_encoder_mode because we will
> know the panel's video/cmd mode in the dsi_bind call
> am i missing something about why mdp5 had this?
>
> From the dpu perspective, since dsi_bind() happens only once panel has
> attached.
>> .snapshot = dpu_kms_mdp_snapshot,
>> #ifdef CONFIG_DEBUG_FS
>> .debugfs_init = dpu_kms_debugfs_init,
--
With best wishes
Dmitry
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