On 2020-06-02 15:12, Daniel Vetter wrote:
> On Sat, May 30, 2020 at 05:14:21AM +0300, Laurent Pinchart wrote:
>> Hi Stefan,
>>
>> On Mon, Mar 23, 2020 at 10:27:21PM +0100, Stefan Agner wrote:
>> > On 2020-03-09 20:51, Laurent Pinchart wrote:
>> > > Replace the manual connector implementation based on drm_panel with the
>> > > drm_panel_bridge helper. This simplifies the mxsfb driver by removing
>> > > connector-related code, and standardizing all pipeline control
>> > > operations on bridges.
>> > >
>> > > A hack is needed to get hold of the connector, as that's our only source
>> > > of bus flags and formats for now. As soon as the bridge API provides us
>> > > with that information this can be fixed.
>> >
>> > This seems like a nice simplification.
>> >
>> > I gave this a go applied on today's drm-misc-next using a Colibri iMX7
>> > (imx7d-colibri-emmc-eval-v3.dts device tree). This device makes use of
>> > the simple panel driver. I get this when booting:
>> >
>> > [ 2.976698] [drm] Supports vblank timestamp caching Rev 2
>> > (21.10.2013).
>> > [ 2.983526] ------------[ cut here ]------------
>> > [ 2.988180] WARNING: CPU: 0 PID: 1 at
>> > drivers/gpu/drm/bridge/panel.c:267 devm_drm_panel_bridge_add+0x25/0x28
>> > [ 2.998059] Modules linked in:
>> > [ 3.001159] CPU: 0 PID: 1 Comm: swapper/0 Not tainted
>> > 5.6.0-rc5-yocto-standard-01250-ga4ce5db7c9f1 #29
>> > [ 3.010493] Hardware name: Freescale i.MX7 Dual (Device Tree)
>> > [ 3.016281] [<c010f089>] (unwind_backtrace) from [<c010a9bb>]
>> > (show_stack+0xb/0xc)
>> > [ 3.023887] [<c010a9bb>] (show_stack) from [<c08b33cf>]
>> > (dump_stack+0x63/0x70)
>> > [ 3.031144] [<c08b33cf>] (dump_stack) from [<c0124385>]
>> > (__warn+0x9d/0xb0)
>> > [ 3.038047] [<c0124385>] (__warn) from [<c0124403>]
>> > (warn_slowpath_fmt+0x6b/0x70)
>> > [ 3.045564] [<c0124403>] (warn_slowpath_fmt) from [<c04ebf65>]
>> > (devm_drm_panel_bridge_add+0x25/0x28)
>> > [ 3.054736] [<c04ebf65>] (devm_drm_panel_bridge_add) from
>> > [<c051fe7f>] (mxsfb_probe+0x197/0x2e0)
>> > [ 3.063559] [<c051fe7f>] (mxsfb_probe) from [<c0532e91>]
>> > (platform_drv_probe+0x2d/0x60)
>> > [ 3.071598] [<c0532e91>] (platform_drv_probe) from [<c0531615>]
>> > (really_probe+0x1dd/0x330)
>> > [ 3.079897] [<c0531615>] (really_probe) from [<c05318b3>]
>> > (driver_probe_device+0x4f/0x154)
>> > [ 3.088195] [<c05318b3>] (driver_probe_device) from [<c0531b3f>]
>> > (device_driver_attach+0x37/0x44)
>> > [ 3.097101] [<c0531b3f>] (device_driver_attach) from [<c0531bc7>]
>> > (__driver_attach+0x7b/0xec)
>> > [ 3.105660] [<c0531bc7>] (__driver_attach) from [<c0530069>]
>> > (bus_for_each_dev+0x3d/0x64)
>> > [ 3.113870] [<c0530069>] (bus_for_each_dev) from [<c0530b9b>]
>> > (bus_add_driver+0xef/0x160)
>> > [ 3.122081] [<c0530b9b>] (bus_add_driver) from [<c053238d>]
>> > (driver_register+0x35/0x9c)
>> > [ 3.130119] [<c053238d>] (driver_register) from [<c0102de9>]
>> > (do_one_initcall+0x3d/0x1e4)
>> > [ 3.138333] [<c0102de9>] (do_one_initcall) from [<c1100d13>]
>> > (kernel_init_freeable+0x1b3/0x1fc)
>> > [ 3.147069] [<c1100d13>] (kernel_init_freeable) from [<c08c3f7b>]
>> > (kernel_init+0x7/0xd0)
>> > [ 3.155194] [<c08c3f7b>] (kernel_init) from [<c01010f9>]
>> > (ret_from_fork+0x11/0x38)
>> > [ 3.162789] Exception stack(0xec0e3fb0 to 0xec0e3ff8)
>> > [ 3.167862] 3fa0: 00000000
>> > 00000000 00000000 00000000
>> > [ 3.176071] 3fc0: 00000000 00000000 00000000 00000000 00000000
>> > 00000000 00000000 00000000
>> > [ 3.184278] 3fe0: 00000000 00000000 00000000 00000000 00000013
>> > 00000000
>> > [ 3.191029] ---[ end trace b69e1f44de470959 ]---
>> > [ 3.195671] mxsfb 30730000.lcdif: Cannot connect bridge: -19
>> >
>> > Should we maybe use devm_drm_panel_bridge_add_typed?
>>
>> As Sam reported, this is caused by the panel not setting connector_type.
>> We could use devm_drm_panel_bridge_add_typed(), even if I like the
>> warning as it uncovers the problematic panels and gets them fixed. What
>> would be your preference ?
>
> Adding warnings everywhere is kinda uncool, at least my experience is that
> if there's too much you get warning overload and train people to ignore
> them.
>
> Imo either hide the wwarning for now, or if it's not too much work, review
> all the panel drivers and make sure they set the connector type somewhere.
> Warnings are kinda ok once you're pretty sure you got them all, and want
> to make sure newly added drivers get this all right. But not before we've
> reached that.
I am with Daniel on this, too many warnings make users blind of them, so
we should save them when really attention is needed.
I guess the only question which connector type we should default to. I
think DRM_MODE_CONNECTOR_DPI make sense for this IP.
--
Stefan
>
> Cheers, Daniel
>
>>
>> > Two more comments below.
>> >
>> > > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>> > > ---
>> > > drivers/gpu/drm/mxsfb/Makefile | 2 +-
>> > > drivers/gpu/drm/mxsfb/mxsfb_drv.c | 105 ++++++++++++++----------------
>> > > drivers/gpu/drm/mxsfb/mxsfb_drv.h | 5 +-
>> > > drivers/gpu/drm/mxsfb/mxsfb_out.c | 99 ----------------------------
>> > > 4 files changed, 53 insertions(+), 158 deletions(-)
>> > > delete mode 100644 drivers/gpu/drm/mxsfb/mxsfb_out.c
>> > >
>> > > diff --git a/drivers/gpu/drm/mxsfb/Makefile b/drivers/gpu/drm/mxsfb/Makefile
>> > > index ff6e358088fa..811584e54ad1 100644
>> > > --- a/drivers/gpu/drm/mxsfb/Makefile
>> > > +++ b/drivers/gpu/drm/mxsfb/Makefile
>> > > @@ -1,3 +1,3 @@
>> > > # SPDX-License-Identifier: GPL-2.0-only
>> > > -mxsfb-y := mxsfb_drv.o mxsfb_crtc.o mxsfb_out.o
>> > > +mxsfb-y := mxsfb_drv.o mxsfb_crtc.o
>> > > obj-$(CONFIG_DRM_MXSFB) += mxsfb.o
>> > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>> > > b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>> > > index 2e6068d96034..cffc70257bd3 100644
>> > > --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>> > > +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
>> > > @@ -29,7 +29,6 @@
>> > > #include <drm/drm_gem_framebuffer_helper.h>
>> > > #include <drm/drm_irq.h>
>> > > #include <drm/drm_of.h>
>> > > -#include <drm/drm_panel.h>
>> > > #include <drm/drm_probe_helper.h>
>> > > #include <drm/drm_simple_kms_helper.h>
>> > > #include <drm/drm_vblank.h>
>> > > @@ -100,29 +99,11 @@ static void mxsfb_pipe_enable(struct
>> > > drm_simple_display_pipe *pipe,
>> > > struct drm_crtc_state *crtc_state,
>> > > struct drm_plane_state *plane_state)
>> > > {
>> > > - struct drm_connector *connector;
>> > > struct mxsfb_drm_private *mxsfb = drm_pipe_to_mxsfb_drm_private(pipe);
>> > > struct drm_device *drm = pipe->plane.dev;
>> > >
>> > > - if (!mxsfb->connector) {
>> > > - list_for_each_entry(connector,
>> > > - &drm->mode_config.connector_list,
>> > > - head)
>> > > - if (connector->encoder == &mxsfb->pipe.encoder) {
>> > > - mxsfb->connector = connector;
>> > > - break;
>> > > - }
>> > > - }
>> > > -
>> > > - if (!mxsfb->connector) {
>> > > - dev_warn(drm->dev, "No connector attached, using default\n");
>> > > - mxsfb->connector = &mxsfb->panel_connector;
>> > > - }
>> > > -
>> > > pm_runtime_get_sync(drm->dev);
>> > > - drm_panel_prepare(mxsfb->panel);
>> > > mxsfb_crtc_enable(mxsfb);
>> > > - drm_panel_enable(mxsfb->panel);
>> > > }
>> > >
>> > > static void mxsfb_pipe_disable(struct drm_simple_display_pipe *pipe)
>> > > @@ -132,9 +113,7 @@ static void mxsfb_pipe_disable(struct
>> > > drm_simple_display_pipe *pipe)
>> > > struct drm_crtc *crtc = &pipe->crtc;
>> > > struct drm_pending_vblank_event *event;
>> > >
>> > > - drm_panel_disable(mxsfb->panel);
>> > > mxsfb_crtc_disable(mxsfb);
>> > > - drm_panel_unprepare(mxsfb->panel);
>> > > pm_runtime_put_sync(drm->dev);
>> > >
>> > > spin_lock_irq(&drm->event_lock);
>> > > @@ -144,9 +123,6 @@ static void mxsfb_pipe_disable(struct
>> > > drm_simple_display_pipe *pipe)
>> > > drm_crtc_send_vblank_event(crtc, event);
>> > > }
>> > > spin_unlock_irq(&drm->event_lock);
>> > > -
>> > > - if (mxsfb->connector != &mxsfb->panel_connector)
>> > > - mxsfb->connector = NULL;
>> > > }
>> > >
>> > > static void mxsfb_pipe_update(struct drm_simple_display_pipe *pipe,
>> > > @@ -190,6 +166,48 @@ static struct drm_simple_display_pipe_funcs mxsfb_funcs = {
>> > > .disable_vblank = mxsfb_pipe_disable_vblank,
>> > > };
>> > >
>> > > +static int mxsfb_attach_bridge(struct mxsfb_drm_private *mxsfb)
>> > > +{
>> > > + struct drm_device *drm = mxsfb->drm;
>> > > + struct drm_connector_list_iter iter;
>> > > + struct drm_panel *panel;
>> > > + struct drm_bridge *bridge;
>> > > + int ret;
>> > > +
>> > > + ret = drm_of_find_panel_or_bridge(drm->dev->of_node, 0, 0, &panel,
>> > > + &bridge);
>> > > + if (ret)
>> > > + return ret;
>> > > +
>> > > + if (panel) {
>> > > + bridge = devm_drm_panel_bridge_add(drm->dev, panel);
>> >
>> > Do we need a select DRM_PANEL_BRIDGE in Kconfig maybe? From what I can
>> > tell there is no devm_drm_panel_bridge_add() stub if DRM_PANEL_BRIDGE is
>> > not selected.
>>
>> You're right, I'll add it.
>>
>> > > + if (IS_ERR(bridge))
>> > > + return PTR_ERR(bridge);
>> > > + }
>> > > +
>> > > + if (!bridge)
>> > > + return -ENODEV;
>> > > +
>> > > + ret = drm_simple_display_pipe_attach_bridge(&mxsfb->pipe, bridge);
>> > > + if (ret) {
>> > > + DRM_DEV_ERROR(drm->dev,
>> > > + "failed to attach bridge: %d\n", ret);
>> > > + return ret;
>> > > + }
>> > > +
>> > > + mxsfb->bridge = bridge;
>> > > +
>> > > + /*
>> > > + * Get hold of the connector. This is a bit of a hack, until the bridge
>> > > + * API gives us bus flags and formats.
>> > > + */
>> > > + drm_connector_list_iter_begin(drm, &iter);
>> > > + mxsfb->connector = drm_connector_list_iter_next(&iter);
>> > > + drm_connector_list_iter_end(&iter);
>> >
>> > Could we not just use drm_panel_bridge_connector() here?
>>
>> There's no guarantee that mxsfb->bridge is a panel bridge, the LCDIF
>> output could be connected to another bridge in which case
>> drm_of_find_panel_or_bridge() will set panel to NULL and bridge to a
>> non-NULL value).
>>
>> > > +
>> > > + return 0;
>> > > +}
>> > > +
>> > > static int mxsfb_load(struct drm_device *drm, unsigned long flags)
>> > > {
>> > > struct platform_device *pdev = to_platform_device(drm->dev);
>> > > @@ -201,6 +219,7 @@ static int mxsfb_load(struct drm_device *drm,
>> > > unsigned long flags)
>> > > if (!mxsfb)
>> > > return -ENOMEM;
>> > >
>> > > + mxsfb->drm = drm;
>> > > drm->dev_private = mxsfb;
>> > > mxsfb->devdata = &mxsfb_devdata[pdev->id_entry->driver_data];
>> > >
>> > > @@ -236,41 +255,17 @@ static int mxsfb_load(struct drm_device *drm,
>> > > unsigned long flags)
>> > > /* Modeset init */
>> > > drm_mode_config_init(drm);
>> > >
>> > > - ret = mxsfb_create_output(drm);
>> > > - if (ret < 0) {
>> > > - dev_err(drm->dev, "Failed to create outputs\n");
>> > > - goto err_vblank;
>> > > - }
>> > > -
>> > > ret = drm_simple_display_pipe_init(drm, &mxsfb->pipe, &mxsfb_funcs,
>> > > - mxsfb_formats, ARRAY_SIZE(mxsfb_formats), NULL,
>> > > - mxsfb->connector);
>> > > + mxsfb_formats, ARRAY_SIZE(mxsfb_formats), NULL, NULL);
>> > > if (ret < 0) {
>> > > dev_err(drm->dev, "Cannot setup simple display pipe\n");
>> > > goto err_vblank;
>> > > }
>> > >
>> > > - /*
>> > > - * Attach panel only if there is one.
>> > > - * If there is no panel attach, it must be a bridge. In this case, we
>> > > - * need a reference to its connector for a proper initialization.
>> > > - * We will do this check in pipe->enable(), since the connector won't
>> > > - * be attached to an encoder until then.
>> > > - */
>> > > -
>> > > - if (mxsfb->panel) {
>> > > - ret = drm_panel_attach(mxsfb->panel, mxsfb->connector);
>> > > - if (ret) {
>> > > - dev_err(drm->dev, "Cannot connect panel: %d\n", ret);
>> > > - goto err_vblank;
>> > > - }
>> > > - } else if (mxsfb->bridge) {
>> > > - ret = drm_simple_display_pipe_attach_bridge(&mxsfb->pipe,
>> > > - mxsfb->bridge);
>> > > - if (ret) {
>> > > - dev_err(drm->dev, "Cannot connect bridge: %d\n", ret);
>> > > - goto err_vblank;
>> > > - }
>> > > + ret = mxsfb_attach_bridge(mxsfb);
>> > > + if (ret) {
>> > > + dev_err(drm->dev, "Cannot connect bridge: %d\n", ret);
>> > > + goto err_vblank;
>> > > }
>> > >
>> > > drm->mode_config.min_width = MXSFB_MIN_XRES;
>> > > @@ -288,7 +283,7 @@ static int mxsfb_load(struct drm_device *drm,
>> > > unsigned long flags)
>> > >
>> > > if (ret < 0) {
>> > > dev_err(drm->dev, "Failed to install IRQ handler\n");
>> > > - goto err_irq;
>> > > + goto err_vblank;
>> > > }
>> > >
>> > > drm_kms_helper_poll_init(drm);
>> > > @@ -299,8 +294,6 @@ static int mxsfb_load(struct drm_device *drm,
>> > > unsigned long flags)
>> > >
>> > > return 0;
>> > >
>> > > -err_irq:
>> > > - drm_panel_detach(mxsfb->panel);
>> > > err_vblank:
>> > > pm_runtime_disable(drm->dev);
>> > >
>> > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.h
>> > > b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
>> > > index 0b65b5194a9c..0e3e5a63bbf9 100644
>> > > --- a/drivers/gpu/drm/mxsfb/mxsfb_drv.h
>> > > +++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.h
>> > > @@ -8,6 +8,8 @@
>> > > #ifndef __MXSFB_DRV_H__
>> > > #define __MXSFB_DRV_H__
>> > >
>> > > +struct drm_device;
>> > > +
>> > > struct mxsfb_devdata {
>> > > unsigned int transfer_count;
>> > > unsigned int cur_buf;
>> > > @@ -26,10 +28,9 @@ struct mxsfb_drm_private {
>> > > struct clk *clk_axi;
>> > > struct clk *clk_disp_axi;
>> > >
>> > > + struct drm_device *drm;
>> > > struct drm_simple_display_pipe pipe;
>> > > - struct drm_connector panel_connector;
>> > > struct drm_connector *connector;
>> > > - struct drm_panel *panel;
>> > > struct drm_bridge *bridge;
>> > > };
>> > >
>> > > diff --git a/drivers/gpu/drm/mxsfb/mxsfb_out.c
>> > > b/drivers/gpu/drm/mxsfb/mxsfb_out.c
>> > > deleted file mode 100644
>> > > index 9eca1605d11d..000000000000
>> > > --- a/drivers/gpu/drm/mxsfb/mxsfb_out.c
>> > > +++ /dev/null
>> > > @@ -1,99 +0,0 @@
>> > > -// SPDX-License-Identifier: GPL-2.0-or-later
>> > > -/*
>> > > - * Copyright (C) 2016 Marek Vasut <marex@xxxxxxx>
>> > > - */
>> > > -
>> > > -#include <linux/of_graph.h>
>> > > -
>> > > -#include <drm/drm_atomic.h>
>> > > -#include <drm/drm_atomic_helper.h>
>> > > -#include <drm/drm_crtc.h>
>> > > -#include <drm/drm_fb_cma_helper.h>
>> > > -#include <drm/drm_gem_cma_helper.h>
>> > > -#include <drm/drm_of.h>
>> > > -#include <drm/drm_panel.h>
>> > > -#include <drm/drm_plane_helper.h>
>> > > -#include <drm/drm_probe_helper.h>
>> > > -#include <drm/drm_simple_kms_helper.h>
>> > > -
>> > > -#include "mxsfb_drv.h"
>> > > -
>> > > -static struct mxsfb_drm_private *
>> > > -drm_connector_to_mxsfb_drm_private(struct drm_connector *connector)
>> > > -{
>> > > - return container_of(connector, struct mxsfb_drm_private,
>> > > - panel_connector);
>> > > -}
>> > > -
>> > > -static int mxsfb_panel_get_modes(struct drm_connector *connector)
>> > > -{
>> > > - struct mxsfb_drm_private *mxsfb =
>> > > - drm_connector_to_mxsfb_drm_private(connector);
>> > > -
>> > > - if (mxsfb->panel)
>> > > - return drm_panel_get_modes(mxsfb->panel, connector);
>> > > -
>> > > - return 0;
>> > > -}
>> > > -
>> > > -static const struct
>> > > -drm_connector_helper_funcs mxsfb_panel_connector_helper_funcs = {
>> > > - .get_modes = mxsfb_panel_get_modes,
>> > > -};
>> > > -
>> > > -static enum drm_connector_status
>> > > -mxsfb_panel_connector_detect(struct drm_connector *connector, bool force)
>> > > -{
>> > > - struct mxsfb_drm_private *mxsfb =
>> > > - drm_connector_to_mxsfb_drm_private(connector);
>> > > -
>> > > - if (mxsfb->panel)
>> > > - return connector_status_connected;
>> > > -
>> > > - return connector_status_disconnected;
>> > > -}
>> > > -
>> > > -static void mxsfb_panel_connector_destroy(struct drm_connector *connector)
>> > > -{
>> > > - struct mxsfb_drm_private *mxsfb =
>> > > - drm_connector_to_mxsfb_drm_private(connector);
>> > > -
>> > > - if (mxsfb->panel)
>> > > - drm_panel_detach(mxsfb->panel);
>> > > -
>> > > - drm_connector_unregister(connector);
>> > > - drm_connector_cleanup(connector);
>> > > -}
>> > > -
>> > > -static const struct drm_connector_funcs mxsfb_panel_connector_funcs = {
>> > > - .detect = mxsfb_panel_connector_detect,
>> > > - .fill_modes = drm_helper_probe_single_connector_modes,
>> > > - .destroy = mxsfb_panel_connector_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,
>> > > -};
>> > > -
>> > > -int mxsfb_create_output(struct drm_device *drm)
>> > > -{
>> > > - struct mxsfb_drm_private *mxsfb = drm->dev_private;
>> > > - int ret;
>> > > -
>> > > - ret = drm_of_find_panel_or_bridge(drm->dev->of_node, 0, 0,
>> > > - &mxsfb->panel, &mxsfb->bridge);
>> > > - if (ret)
>> > > - return ret;
>> > > -
>> > > - if (mxsfb->panel) {
>> > > - mxsfb->connector = &mxsfb->panel_connector;
>> > > - mxsfb->connector->dpms = DRM_MODE_DPMS_OFF;
>> > > - mxsfb->connector->polled = 0;
>> > > - drm_connector_helper_add(mxsfb->connector,
>> > > - &mxsfb_panel_connector_helper_funcs);
>> > > - ret = drm_connector_init(drm, mxsfb->connector,
>> > > - &mxsfb_panel_connector_funcs,
>> > > - DRM_MODE_CONNECTOR_Unknown);
>> > > - }
>> > > -
>> > > - return ret;
>> > > -}
>>
>> --
>> Regards,
>>
>> Laurent Pinchart
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@xxxxxxxxxxxxxxxxxxxxx
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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