On Thu, Oct 13, 2022 at 3:39 AM Robert Foss <robert.foss@xxxxxxxxxx> wrote:
>
> On Tue, 11 Oct 2022 at 23:11, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> >
> > adv7533 bridge tries to dynamically switch lanes based on the
> > mode by detaching and attaching the mipi dsi device.
> >
> > This approach is incorrect because this method of dynamic switch of
> > detaching and attaching the mipi dsi device also results in removing
> > and adding the component which is not necessary.
> >
> > This approach is also prone to deadlocks. So for example, on the
> > db410c whenever this path is executed with lockdep enabled,
> > this results in a deadlock due to below ordering of locks.
> >
> > -> #1 (crtc_ww_class_acquire){+.+.}-{0:0}:
> > lock_acquire+0x6c/0x90
> > drm_modeset_acquire_init+0xf4/0x150
> > drmm_mode_config_init+0x220/0x770
> > msm_drm_bind+0x13c/0x654
> > try_to_bring_up_aggregate_device+0x164/0x1d0
> > __component_add+0xa8/0x174
> > component_add+0x18/0x2c
> > dsi_dev_attach+0x24/0x30
> > dsi_host_attach+0x98/0x14c
> > devm_mipi_dsi_attach+0x38/0xb0
> > adv7533_attach_dsi+0x8c/0x110
> > adv7511_probe+0x5a0/0x930
> > i2c_device_probe+0x30c/0x350
> > really_probe.part.0+0x9c/0x2b0
> > __driver_probe_device+0x98/0x144
> > driver_probe_device+0xac/0x14c
> > __device_attach_driver+0xbc/0x124
> > bus_for_each_drv+0x78/0xd0
> > __device_attach+0xa8/0x1c0
> > device_initial_probe+0x18/0x24
> > bus_probe_device+0xa0/0xac
> > deferred_probe_work_func+0x90/0xd0
> > process_one_work+0x28c/0x6b0
> > worker_thread+0x240/0x444
> > kthread+0x110/0x114
> > ret_from_fork+0x10/0x20
> >
> > -> #0 (component_mutex){+.+.}-{3:3}:
> > __lock_acquire+0x1280/0x20ac
> > lock_acquire.part.0+0xe0/0x230
> > lock_acquire+0x6c/0x90
> > __mutex_lock+0x84/0x400
> > mutex_lock_nested+0x3c/0x70
> > component_del+0x34/0x170
> > dsi_dev_detach+0x24/0x30
> > dsi_host_detach+0x20/0x64
> > mipi_dsi_detach+0x2c/0x40
> > adv7533_mode_set+0x64/0x90
> > adv7511_bridge_mode_set+0x210/0x214
> > drm_bridge_chain_mode_set+0x5c/0x84
> > crtc_set_mode+0x18c/0x1dc
> > drm_atomic_helper_commit_modeset_disables+0x40/0x50
> > msm_atomic_commit_tail+0x1d0/0x6e0
> > commit_tail+0xa4/0x180
> > drm_atomic_helper_commit+0x178/0x3b0
> > drm_atomic_commit+0xa4/0xe0
> > drm_client_modeset_commit_atomic+0x228/0x284
> > drm_client_modeset_commit_locked+0x64/0x1d0
> > drm_client_modeset_commit+0x34/0x60
> > drm_fb_helper_lastclose+0x74/0xcc
> > drm_lastclose+0x3c/0x80
> > drm_release+0xfc/0x114
> > __fput+0x70/0x224
> > ____fput+0x14/0x20
> > task_work_run+0x88/0x1a0
> > do_exit+0x350/0xa50
> > do_group_exit+0x38/0xa4
> > __wake_up_parent+0x0/0x34
> > invoke_syscall+0x48/0x114
> > el0_svc_common.constprop.0+0x60/0x11c
> > do_el0_svc+0x30/0xc0
> > el0_svc+0x58/0x100
> > el0t_64_sync_handler+0x1b0/0x1bc
> > el0t_64_sync+0x18c/0x190
> >
> > Due to above reasons, remove the dynamic lane switching
> > code from adv7533 bridge chip and filter out the modes
> > which would need different number of lanes as compared
> > to the initialization time using the mode_valid callback.
> >
> > This can be potentially re-introduced by using the pre_enable()
> > callback but this needs to be evaluated first whether such an
> > approach will work so this will be done with a separate change.
> >
> > changes since RFC:
> > - Fix commit text and add TODO comment
> >
> > changes in v2:
> > - Fix checkpatch formatting errors
> >
> > Fixes: 62b2f026cd8e ("drm/bridge: adv7533: Change number of DSI lanes dynamically")
> > Closes: https://gitlab.freedesktop.org/drm/msm/-/issues/16
> > Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > Reviewed-by: Robert Foss <robert.foss@xxxxxxxxxx>
> > Link: https://lore.kernel.org/r/1661797363-7564-1-git-send-email-quic_abhinavk@xxxxxxxxxxx
> > ---
> > drivers/gpu/drm/bridge/adv7511/adv7511.h | 3 ++-
> > drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 18 ++++++++++++++----
> > drivers/gpu/drm/bridge/adv7511/adv7533.c | 25 +++++++++++++------------
> > 3 files changed, 29 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511.h b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> > index a031a0cd1f18..1053d185b24c 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7511.h
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511.h
> > @@ -405,7 +405,8 @@ static inline int adv7511_cec_init(struct device *dev, struct adv7511 *adv7511)
> >
> > void adv7533_dsi_power_on(struct adv7511 *adv);
> > void adv7533_dsi_power_off(struct adv7511 *adv);
> > -void adv7533_mode_set(struct adv7511 *adv, const struct drm_display_mode *mode);
> > +enum drm_mode_status adv7533_mode_valid(struct adv7511 *adv,
> > + const struct drm_display_mode *mode);
> > int adv7533_patch_registers(struct adv7511 *adv);
> > int adv7533_patch_cec_registers(struct adv7511 *adv);
> > int adv7533_attach_dsi(struct adv7511 *adv);
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > index 38bf28720f3a..4bc7aac94a16 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
> > @@ -697,7 +697,7 @@ adv7511_detect(struct adv7511 *adv7511, struct drm_connector *connector)
> > }
> >
> > static enum drm_mode_status adv7511_mode_valid(struct adv7511 *adv7511,
> > - struct drm_display_mode *mode)
> > + const struct drm_display_mode *mode)
> > {
> > if (mode->clock > 165000)
> > return MODE_CLOCK_HIGH;
> > @@ -791,9 +791,6 @@ static void adv7511_mode_set(struct adv7511 *adv7511,
> > regmap_update_bits(adv7511->regmap, 0x17,
> > 0x60, (vsync_polarity << 6) | (hsync_polarity << 5));
> >
> > - if (adv7511->type == ADV7533 || adv7511->type == ADV7535)
> > - adv7533_mode_set(adv7511, adj_mode);
> > -
> > drm_mode_copy(&adv7511->curr_mode, adj_mode);
> >
> > /*
> > @@ -913,6 +910,18 @@ static void adv7511_bridge_mode_set(struct drm_bridge *bridge,
> > adv7511_mode_set(adv, mode, adj_mode);
> > }
> >
> > +static enum drm_mode_status adv7511_bridge_mode_valid(struct drm_bridge *bridge,
> > + const struct drm_display_info *info,
> > + const struct drm_display_mode *mode)
> > +{
> > + struct adv7511 *adv = bridge_to_adv7511(bridge);
> > +
> > + if (adv->type == ADV7533 || adv->type == ADV7535)
> > + return adv7533_mode_valid(adv, mode);
> > + else
> > + return adv7511_mode_valid(adv, mode);
> > +}
> > +
> > static int adv7511_bridge_attach(struct drm_bridge *bridge,
> > enum drm_bridge_attach_flags flags)
> > {
> > @@ -960,6 +969,7 @@ static const struct drm_bridge_funcs adv7511_bridge_funcs = {
> > .enable = adv7511_bridge_enable,
> > .disable = adv7511_bridge_disable,
> > .mode_set = adv7511_bridge_mode_set,
> > + .mode_valid = adv7511_bridge_mode_valid,
> > .attach = adv7511_bridge_attach,
> > .detect = adv7511_bridge_detect,
> > .get_edid = adv7511_bridge_get_edid,
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > index ef6270806d1d..258c79d4dab0 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > @@ -100,26 +100,27 @@ void adv7533_dsi_power_off(struct adv7511 *adv)
> > regmap_write(adv->regmap_cec, 0x27, 0x0b);
> > }
> >
> > -void adv7533_mode_set(struct adv7511 *adv, const struct drm_display_mode *mode)
> > +enum drm_mode_status adv7533_mode_valid(struct adv7511 *adv,
> > + const struct drm_display_mode *mode)
> > {
> > + int lanes;
> > struct mipi_dsi_device *dsi = adv->dsi;
> > - int lanes, ret;
> > -
> > - if (adv->num_dsi_lanes != 4)
> > - return;
> >
> > if (mode->clock > 80000)
> > lanes = 4;
> > else
> > lanes = 3;
I know this thread is a bit old, but I have an i.MX8M Mini with an
adv7535 HDMI bridge, and I'm able to display video on a 4-lane
interface with a clock as low as 27000.
> >
> > - if (lanes != dsi->lanes) {
> > - mipi_dsi_detach(dsi);
> > - dsi->lanes = lanes;
> > - ret = mipi_dsi_attach(dsi);
> > - if (ret)
> > - dev_err(&dsi->dev, "failed to change host lanes\n");
> > - }
> > + /*
> > + * TODO: add support for dynamic switching of lanes
> > + * by using the bridge pre_enable() op . Till then filter
> > + * out the modes which shall need different number of lanes
> > + * than what was configured in the device tree.
> > + */
> > + if (lanes != dsi->lanes)
> > + return MODE_BAD;
> > +
My board doesn't currently support dynamic switching, but I'd like to
keep 4-lanes all the time. However, this return eliminates several
resolutions that I can successfully display.
I'd like to eliminate this error, so it works on the imx8m
mini/nano/plus, but I am not sure the best approach without breaking
someone else's board.
I was thinking I could add a flag to disable dynamic switching. If
that flag is set, we'd return MODE_OK here.
Does anyone have any suggestions on an apporach?
adam
> > + return MODE_OK;
> > }
> >
> > int adv7533_patch_registers(struct adv7511 *adv)
> > --
> > 2.7.4
> >
>
> Applied to drm-misc-next.
