[PATCH v2] drm/bridge: adv7533: remove dynamic lane switching from adv7533 bridge
Adam Ford
aford173 at gmail.com
Sat Mar 11 22:40:50 UTC 2023
On Sat, Mar 11, 2023 at 4:02 PM Dmitry Baryshkov
<dmitry.baryshkov at linaro.org> wrote:
>
> On 11/03/2023 23:53, Adam Ford wrote:
> > On Sat, Mar 11, 2023 at 3:40 PM Dmitry Baryshkov
> > <dmitry.baryshkov at linaro.org> wrote:
> >>
> >> "Hi Abhinav,
> >>
> >> On Sat, 11 Mar 2023 at 23:18, Abhinav Kumar <quic_abhinavk at quicinc.com> wrote:
> >>>
> >>> Hi Adam
> >>>
> >>> On 3/11/2023 9:28 AM, Adam Ford wrote:
> >>>> On Thu, Oct 13, 2022 at 3:39 AM Robert Foss <robert.foss at linaro.org> wrote:
> >>>>>
> >>>>> On Tue, 11 Oct 2022 at 23:11, Abhinav Kumar <quic_abhinavk at quicinc.com> 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 at linaro.org>
> >>>>>> Signed-off-by: Abhinav Kumar <quic_abhinavk at quicinc.com>
> >>>>>> Reviewed-by: Robert Foss <robert.foss at linaro.org>
> >>>>>> Link: https://lore.kernel.org/r/1661797363-7564-1-git-send-email-quic_abhinavk@quicinc.com
> >>>>>> ---
> >>>>>> 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.
> >>>>
> >>>
> >>> Looks like this condition is not tracking how low the bridge can support
> >>> with 4 lanes but how high you can support with 3 lanes. Thats the issue.
> >>>
> >>> This condition has been this way since the original bridge driver:
> >>>
> >>> drm/bridge: adv7533: Change number of DSI lanes dynamically
> >>>
> >>> Yes, its possible that with 4 lanes you can support a lower rate but
> >>> with 3 lanes you cannot support a higher one. So that needs to be handled.
> >>>
> >>> The extra conditional's intention was to make sure that if you try to
> >>> switch to a mode which has a different number of lanes than what was set
> >>> in the device tree (basically dynamic mode switch) then fail that.
> >>>
> >>> So perhaps this condition can be modified to :
> >>>
> >>> if (num_dsi_lanes < 4 && mode->clock > 80000)
> >>> return MODE_BAD;
> >>>
> >>> I think that should fix your issue. You can set the number of lanes to 4
> >>> for your board if it supports that using the DT node adi,dsi-lanes.
> >>
> >
> > Thanks to both of you for the ideas.
> >
> >> I went on and looked into the adv7533 datasheet. Strangely enough
> >> these conditions do not correspond to the limitations from the
> >> datasheet:
> >> - "pixel clocks of up to 80 MHz",
> >> - "each [DSI lane] running up to 800 Mbps"
> >>
> >> So probably the conditions should be as following:
> >>
> >> if (mode->clock > 80000)
> >> return MODE_CLOCK_HIGH;
> >
> > This is consistent with what is happening on the 7511.
> >
> >>
> >> if (mode->clock * bpp > 800000 * adv->num_dsi_lanes)
> >> return MODE_CLOCK_HIGH;
> >>
> >> See https://www.analog.com/media/en/technical-documentation/data-sheets/adv7533.pdf
> >
> > These numbers would need to be changed for the 7535, the device I am
> > using. So I'll submit a patch which checks these with different max
> > values depending on whether or not the device is 7533 or 7535.
>
> For adv7535 the max pixel clock seems to 148.5 MHz, max lane clock is
> 891 MHz.
>
> I'm slightly confused about adv7511, whose datasheet contains just a
> single number of '225 MHz'.
This is what I did:
u8 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
...
/* Check max clock for either 7533 or 7535 */
if (mode->clock > (adv->type == ADV7533 ? 80000 : 148500))
return MODE_CLOCK_HIGH;
/* Check max clock for each lane */
max_lane_freq = (adv->type == ADV7533 ? 800000 : 891000);
if (mode->clock * bpp > max_lane_freq * adv->num_dsi_lanes)
return MODE_CLOCK_HIGH;
Does that look OK to everyone?
If so, I'll push a formal patch with a fixes tag.
adam
>
> >
> > adam
> >
> >>
> >>>
> >>>>>>
> >>>>>> - 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
> >>>>
> >>>
> >>> I am thinking of this solution
> >>>
> >>> if (num_dsi_lanes < 4 && mode->clock > 80000)
> >>> return MODE_BAD;
> >>>
> >>> So lets say some user tried to set number of lanes to 3 but tries a mode
> >>> needing > 80000 clock then fail.
> >>>
> >>> That way we still dont support dynamic mode switch but also dont limit
> >>> the modes which can be supported with 4 lanes.
> >>>
> >>>>
> >>>>>> + return MODE_OK;
> >>>>>> }
> >>>>>>
> >>>>>> int adv7533_patch_registers(struct adv7511 *adv)
> >>>>>> --
> >>>>>> 2.7.4
> >>>>>>
> >>>>>
> >>>>> Applied to drm-misc-next.
> >>
> >>
> >>
> >> --
> >> With best wishes
> >> Dmitry
>
> --
> With best wishes
> Dmitry
>
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