[PATCH v2] drm/bridge: adv7533: remove dynamic lane switching from adv7533 bridge
Adam Ford
aford173 at gmail.com
Sat Mar 11 22:52:45 UTC 2023
On Sat, Mar 11, 2023 at 4:42 PM Dmitry Baryshkov
<dmitry.baryshkov at linaro.org> wrote:
>
> On 12/03/2023 00:40, Adam Ford wrote:
> > 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
>
> LGTM. You might want to split this to two separate functions (7533 vs
> 7535), but it's up to your taste.
I intentionally wanted to keep them together since the 7535 uses the
code from the 7533, and I thought it was simpler to do the check in
one place instead of having two sets of nearly identical checks.
I'm just finishing the clean-up, so the patch should go out momentarily.
adam
>
> .
> >
> > 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
> >>
>
> --
> With best wishes
> Dmitry
>
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