[PATCH v2] drm/bridge: adv7533: remove dynamic lane switching from adv7533 bridge
Dmitry Baryshkov
dmitry.baryshkov at linaro.org
Sat Mar 11 22:42:25 UTC 2023
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.
.
>
> 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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