From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0B25FC433F5 for ; Sun, 24 Apr 2022 19:59:46 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 06EE210E1E0; Sun, 24 Apr 2022 19:59:46 +0000 (UTC) Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2688210E1E0; Sun, 24 Apr 2022 19:59:44 +0000 (UTC) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 18CD93E4; Sun, 24 Apr 2022 21:59:42 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1650830382; bh=w85Qs7iJQJiiPcDnqoEQlTbwC5z2yA11QeJy5zqZ/IY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rS9scZ7VdOObKZoExLEIb89ioQx4aEsIpTO8S7+9VVc0lDX0lSMDEB02fwlT7GEkP XNbBKzwodTjGYGtpPsBil5sw+96sthZNwL/rnqIMlY53IUx9GgDyCRJa5gTsW6k9oy H+Co2Ty542tDl/RAGT5XqsAxQD+sz23RuwZ3AfWU= Date: Sun, 24 Apr 2022 22:59:41 +0300 From: Laurent Pinchart To: Abhinav Kumar Subject: Re: [Freedreno] [PATCH v4 03/20] drm: allow real encoder to be passed for drm_writeback_connector Message-ID: References: <1650668815-7048-1-git-send-email-quic_abhinavk@quicinc.com> <1650668815-7048-4-git-send-email-quic_abhinavk@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: markyacoub@chromium.org, liviu.dudau@arm.com, dri-devel@lists.freedesktop.org, swboyd@chromium.org, seanpaul@chromium.org, dmitry.baryshkov@linaro.org, quic_jesszhan@quicinc.com, quic_aravindh@quicinc.com, freedreno@lists.freedesktop.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Abhinav, On Sun, Apr 24, 2022 at 11:23:20AM -0700, Abhinav Kumar wrote: > On 4/24/2022 11:12 AM, Abhinav Kumar wrote: > > On 4/24/2022 7:50 AM, Laurent Pinchart wrote: > >> On Fri, Apr 22, 2022 at 04:06:38PM -0700, Abhinav Kumar wrote: > >>> For some vendor driver implementations, display hardware can > >>> be shared between the encoder used for writeback and the physical > >>> display. > >>> > >>> In addition resources such as clocks and interrupts can > >>> also be shared between writeback and the real encoder. > >>> > >>> To accommodate such vendor drivers and hardware, allow > >>> real encoder to be passed for drm_writeback_connector. > >>> > >>> For existing clients, drm_writeback_connector_init() will use > >>> an internal_encoder under the hood and hence no changes will > >>> be needed. > >>> > >>> changes in v7: > >>>     - move this change before the vc4 change in the series > >>>       to minimize the changes to vendor drivers in drm core > >>>       changes > >> > >> Why is this needed ? The drm_writeback_connector functions don't need > >> the drm_encoder after drm_writeback_connector_init() (or > >> drm_writeback_connector_init_with_encoder()) returns. > >> > > > > Sorry I didnt follow this comment. This change log is incorrect, so > > after changing the previous change in the series and modifying this, no > > further changes are needed to vc4, so I decided to drop the next change. > > So this change log is incorrect. I can remove this. > > > > Is that what you meant? > > So till the previous change, the only user of > drm_writeback_connector_init_with_encoder() was > drm_writeback_connector_init() which was still passing its own > internal_encoder. > > Only if the wb_connector->encoder is changed to a pointer, other vendor > drivers can pass their own encoder to > drm_writeback_connector_init_with_encoder(). > > Hence you are right that drm_writeback_connector functions do not need > drm_encoder after init() returns, but till this change is done, other > vendor drivers cannot directly call > drm_writeback_connector_init_with_encoder() because the encoder will not > be valid till then. Users of drm_writeback_connector_init_with_encoder() handle the encoder themselves, they can simply ignore drm_writeback_connector.encoder. The documentation of the encoder field needs to be updated though (I'd do so in the previous patch), to clearly mention that the field is valid only when using drm_writeback_connector_init(), not when calling drm_writeback_connector_init_with_encoder(). > Hope this clarifies it. > > >>> Signed-off-by: Abhinav Kumar > >>> Reviewed-by: Dmitry Baryshkov > >>> --- > >>>   drivers/gpu/drm/drm_writeback.c | 18 ++++++++++++------ > >>>   drivers/gpu/drm/vc4/vc4_txp.c   |  4 ++-- > >>>   include/drm/drm_writeback.h     | 22 ++++++++++++++++++++-- > >>>   3 files changed, 34 insertions(+), 10 deletions(-) > >>> > >>> diff --git a/drivers/gpu/drm/drm_writeback.c > >>> b/drivers/gpu/drm/drm_writeback.c > >>> index 92658ad..0538674 100644 > >>> --- a/drivers/gpu/drm/drm_writeback.c > >>> +++ b/drivers/gpu/drm/drm_writeback.c > >>> @@ -180,21 +180,21 @@ int drm_writeback_connector_init(struct > >>> drm_device *dev, > >>>   { > >>>       int ret = 0; > >>> -    drm_encoder_helper_add(&wb_connector->encoder, enc_helper_funcs); > >>> +    drm_encoder_helper_add(&wb_connector->internal_encoder, enc_helper_funcs); > >>> -    wb_connector->encoder.possible_crtcs = possible_crtcs; > >>> +    wb_connector->internal_encoder.possible_crtcs = possible_crtcs; > >>> -    ret = drm_encoder_init(dev, &wb_connector->encoder, > >>> +    ret = drm_encoder_init(dev, &wb_connector->internal_encoder, > >>>                      &drm_writeback_encoder_funcs, > >>>                      DRM_MODE_ENCODER_VIRTUAL, NULL); > >>>       if (ret) > >>>           return ret; > >>> -    ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, &wb_connector->encoder, > >>> -            con_funcs, formats, n_formats); > >>> +    ret = drm_writeback_connector_init_with_encoder(dev, wb_connector, > >>> +            &wb_connector->internal_encoder, con_funcs, formats, n_formats); > >>>       if (ret) > >>> -        drm_encoder_cleanup(&wb_connector->encoder); > >>> +        drm_encoder_cleanup(&wb_connector->internal_encoder); > >>>       return ret; > >>>   } > >>> @@ -239,6 +239,12 @@ int drm_writeback_connector_init_with_encoder(struct drm_device *dev, > >>>       struct drm_mode_config *config = &dev->mode_config; > >>>       int ret = create_writeback_properties(dev); > >>> +    /* > >>> +     * Assign the encoder passed to this API to the wb_connector's encoder. > >>> +     * For drm_writeback_connector_init(), this shall be the internal_encoder > >>> +     */ > >>> +    wb_connector->encoder = enc; > >>> + > >>>       if (ret != 0) > >>>           return ret; > >>> diff --git a/drivers/gpu/drm/vc4/vc4_txp.c b/drivers/gpu/drm/vc4/vc4_txp.c > >>> index 3447eb6..7e063a9 100644 > >>> --- a/drivers/gpu/drm/vc4/vc4_txp.c > >>> +++ b/drivers/gpu/drm/vc4/vc4_txp.c > >>> @@ -159,7 +159,7 @@ struct vc4_txp { > >>>   static inline struct vc4_txp *encoder_to_vc4_txp(struct drm_encoder *encoder) > >>>   { > >>> -    return container_of(encoder, struct vc4_txp, connector.encoder); > >>> +    return container_of(encoder, struct vc4_txp, connector.internal_encoder); > >>>   } > >>>   static inline struct vc4_txp *connector_to_vc4_txp(struct drm_connector *conn) > >>> @@ -507,7 +507,7 @@ static int vc4_txp_bind(struct device *dev, struct device *master, void *data) > >>>       if (ret) > >>>           return ret; > >>> -    encoder = &txp->connector.encoder; > >>> +    encoder = txp->connector.encoder; > >>>       encoder->possible_crtcs = drm_crtc_mask(crtc); > >>>       ret = devm_request_irq(dev, irq, vc4_txp_interrupt, 0, > >>> diff --git a/include/drm/drm_writeback.h b/include/drm/drm_writeback.h > >>> index bb306fa..3fbae9d 100644 > >>> --- a/include/drm/drm_writeback.h > >>> +++ b/include/drm/drm_writeback.h > >>> @@ -25,13 +25,31 @@ struct drm_writeback_connector { > >>>       struct drm_connector base; > >>>       /** > >>> -     * @encoder: Internal encoder used by the connector to fulfill > >>> +     * @encoder: handle to drm_encoder used by the connector to fulfill > >>>        * the DRM framework requirements. The users of the > >>>        * @drm_writeback_connector control the behaviour of the @encoder > >>>        * by passing the @enc_funcs parameter to drm_writeback_connector_init() > >>>        * function. > >>> +     * > >>> +     * For some vendor drivers, the hardware resources are shared between > >>> +     * writeback encoder and rest of the display pipeline. > >>> +     * To accommodate such cases, encoder is a handle to the real encoder > >>> +     * hardware. > >>> +     * > >>> +     * For current existing writeback users, this shall continue to be the > >>> +     * embedded encoder for the writeback connector. > >>> +     */ > >>> +    struct drm_encoder *encoder; > >>> + > >>> +    /** > >>> +     * @internal_encoder: internal encoder used by writeback when > >>> +     * drm_writeback_connector_init() is used. > >>> +     * @encoder will be assigned to this for those cases > >>> +     * > >>> +     * This will be unused when drm_writeback_connector_init_with_encoder() > >>> +     * is used. > >>>        */ > >>> -    struct drm_encoder encoder; > >>> +    struct drm_encoder internal_encoder; > >>>       /** > >>>        * @pixel_formats_blob_ptr: -- Regards, Laurent Pinchart