by Rasmus Villemoes

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Subject: Re: [PATCH v4 0/6] drm: lcdif: Add i.MX93 LCDIF support

On 17/02/2023 09.18, Alexander Stein wrote:
> Hi Liu,
>
> Am Freitag, 17. Februar 2023, 07:54:01 CET schrieb Liu Ying:
>> Hi,
>>
>> This patch set aims to add i.MX93 LCDIF display controller support
>> in the existing LCDIF DRM driver. The LCDIF embedded in i.MX93 SoC
>> is essentially the same to those embedded in i.MX8mp SoC. Through
>> internal bridges, i.MX93 LCDIF may drive a MIPI DSI display or a LVDS
>> display or a parallel display.
>>
>> Patch 1/6 adds device tree binding support for i.MX93 LCDIF in the
>> existing fsl,lcdif.yaml.
>>
>> Patch 2/6 drops lcdif->bridge NULL pointer check as a cleanup patch.
>>
>> Patch 3/6~5/6 prepare for adding i.MX93 LCDIF support step by step.
>>
>> Patch 6/6 adds i.MX93 LCDIF compatible string as the last step of
>> adding i.MX93 LCDIF support.
>
> Thanks for the series. I could test this on my TQMa93xxLA/MBa93xxCA with a
> single LVDS display attached, so no DSI or parallel display. Hence I could not
> test the bus format and flags checks, but they look okay.
> So you can add
> Tested-by: Alexander Stein <[email protected]>
> to the whole series as well.
>
> One thing I noticed is that, sometimes it seems that before probing lcdif my
> system completely freezes. Adding some debug output it seems that's during
> powering up the IMX93_MEDIABLK_PD_LCDIF power domain there is some race
> condition. But adding more more detailed output made the problem go away.
> Did you notice something similar? It might be a red hering though.

Interesting. Sounds similar to what I encountered on several
imx8mp-based boards, both the NXP EVK and our custom design, running a
mainline U-Boot and downstream NXP kernel:

https://lore.kernel.org/u-boot/[email protected]/

I never really found a real solution, but as the hack I ended up
applying in U-Boot does involve some clock settings, and you apparently
now figured out some connection to "overclocking", I do think these
issues are related.

Rasmus

2023-02-20 12:47:46

by Liu Ying

[permalink] [raw]

Subject: Re: [PATCH v4 0/6] drm: lcdif: Add i.MX93 LCDIF support

On Mon, 2023-02-20 at 11:16 +0100, Alexander Stein wrote:
> Hi Liu,

Hi Alexander,

>
> Am Montag, 20. Februar 2023, 09:55:19 CET schrieb Alexander Stein:
> > Hi Liu,
> >
> > Am Freitag, 17. Februar 2023, 09:59:14 CET schrieb Liu Ying:
> > > On Fri, 2023-02-17 at 09:18 +0100, Alexander Stein wrote:
> > > > Hi Liu,
> > >
> > > Hi Alexander,
> > >
> > > > Am Freitag, 17. Februar 2023, 07:54:01 CET schrieb Liu Ying:
> > > > > Hi,
> > > > >
> > > > > This patch set aims to add i.MX93 LCDIF display controller
> > > > > support
> > > > > in the existing LCDIF DRM driver. The LCDIF embedded in
> > > > > i.MX93 SoC
> > > > > is essentially the same to those embedded in i.MX8mp
> > > > > SoC. Through
> > > > > internal bridges, i.MX93 LCDIF may drive a MIPI DSI display
> > > > > or a LVDS
> > > > > display or a parallel display.
> > > > >
> > > > > Patch 1/6 adds device tree binding support for i.MX93 LCDIF
> > > > > in the
> > > > > existing fsl,lcdif.yaml.
> > > > >
> > > > > Patch 2/6 drops lcdif->bridge NULL pointer check as a cleanup
> > > > > patch.
> > > > >
> > > > > Patch 3/6~5/6 prepare for adding i.MX93 LCDIF support step by
> > > > > step.
> > > > >
> > > > > Patch 6/6 adds i.MX93 LCDIF compatible string as the last
> > > > > step of
> > > > > adding i.MX93 LCDIF support.
> > > >
> > > > Thanks for the series. I could test this on my
> > > > TQMa93xxLA/MBa93xxCA with
> > > > a
> > > > single LVDS display attached, so no DSI or parallel display.
> > > > Hence I
> > > > could
> > > > not test the bus format and flags checks, but they look okay.
> > > > So you can add
> > > > Tested-by: Alexander Stein <[email protected]>
> > > > to the whole series as well.
> > >
> > > Thanks for your test.
> > >
> > > > One thing I noticed is that, sometimes it seems that before
> > > > probing
> > > > lcdif
> > > > my system completely freezes. Adding some debug output it seems
> > > > that's
> > > > during powering up the IMX93_MEDIABLK_PD_LCDIF power domain
> > > > there is
> > > > some
> > > > race condition. But adding more more detailed output made the
> > > > problem go
> > > > away. Did you notice something similar? It might be a red
> > > > hering though.
> > >
> > > I don't see system freezing with my i.MX93 11x11 EVK when probing
> > > lcdif. I did try to boot the system several times. All look ok.
> > > This is
> > > a snippet of dmesg when lcdif probes:
> > >
> > > --------------------------8<-------------------------------------
> > > -----
> > > [ 0.753083] Serial: 8250/16550 driver, 4 ports, IRQ sharing
> > > enabled
> > > [ 0.761669] SuperH (H)SCI(F) driver initialized
> > > [ 0.766523] msm_serial: driver initialized
> > > [ 0.780523] printk: console [ttyLP0] enabled0x44380010 (irq =
> > > 16,
> > > base_baud = 1500000) is a FSL_LPUART
> > > [ 0.780523] printk: console [ttyLP0] enabled
> > > [ 0.788928] printk: bootconsole [lpuart32] disabled
> > > [ 0.788928] printk: bootconsole [lpuart32] disabled
> > > [ 0.804632] panel-simple lvds_panel: supply power not found,
> > > using
> > > dummy regulator
> > > [ 0.814741] [drm] Initialized imx-lcdif 1.0.0 20220417 for
> > > 4ae30000.lcd-controller on minor 0
> > > [ 1.195930] Console: switching to colour frame buffer device
> > > 160x50
> > > [ 1.218385] imx-lcdif 4ae30000.lcd-controller: [drm] fb0: imx-
> > > lcdifdrmfb frame buffer device
> > > [ 1.227099] cacheinfo: Unable to detect cache hierarchy for
> > > CPU 0
> > > [ 1.236725] loop: module loaded
> > > --------------------------8<-------------------------------------
> > > -----
> > >
> > > ~300 milliseconds are consumed by the enablement delay required
> > > by the
> > > "boe,ev121wxm-n10-1850" LVDS panel I use.
> >
> > It seems you have the drivers compiled in. I use modules in my case
> > and
> > simple-panel as well. But this is unrelated, because lcdif_probe()
> > is yet to
> > be called. Using the debug diff from below I get the following
> > output:
> >
> > [ 16.111197] imx93-blk-ctrl 4ac10000.system-controller:
> > imx93_blk_ctrl_power_on: 1
> > [ 16.122491] imx93-blk-ctrl 4ac10000.system-controller:
> > imx93_blk_ctrl_power_on: 2
> > [ 16.137766] imx93-blk-ctrl 4ac10000.system-controller:
> > imx93_blk_ctrl_power_on: 3
> > [ 16.154905] imx93-blk-ctrl 4ac10000.system-controller:
> > imx93_blk_ctrl_power_on: 4
> >
> > It seems setting BLK_CLK_EN blocks the whole system, even reading
> > is not
> > possible. I don't have any details on the hardware, but it seems
> > that either
> > some clock or power domain is not enabled. This can also happen if
> > I'm
> > loading the lcdif module manually after boot. But I can't detect
> > any
> > differences in / sys/kernel/debug/clk/clk_summary.
>
> I think I found the cause. It's the maximum clock frequency for
> media_axi and
> media_apb. These clocks were not explicitly configured, most
> probably
> exceeding the maximum frequency allowed.

Thanks for sharing the cause. I use 400MHz media_axi and 133MHz
media_apb.

Regards,
Liu Ying

>
> Best regards,
> Alexander
>
> > ---8<---
> > diff --git a/drivers/soc/imx/imx93-blk-ctrl.c
> > b/drivers/soc/imx/imx93-blk-
> > ctrl.c
> > index 2c600329436cf..50aeb20ce90dc 100644
> > --- a/drivers/soc/imx/imx93-blk-ctrl.c
> > +++ b/drivers/soc/imx/imx93-blk-ctrl.c
> > @@ -129,12 +129,14 @@ static int imx93_blk_ctrl_power_on(struct
> > generic_pm_domain *genpd)
> > struct imx93_blk_ctrl *bc = domain->bc;
> > int ret;
> >
> > + dev_info(bc->dev, "%s: 1\n", __func__);
> > ret = clk_bulk_prepare_enable(bc->num_clks, bc->clks);
> > if (ret) {
> > dev_err(bc->dev, "failed to enable bus clocks\n");
> > return ret;
> > }
> >
> > + dev_info(bc->dev, "%s: 2\n", __func__);
> > ret = clk_bulk_prepare_enable(data->num_clks, domain->clks);
> > if (ret) {
> > clk_bulk_disable_unprepare(bc->num_clks, bc->clks);
> > @@ -142,6 +144,7 @@ static int imx93_blk_ctrl_power_on(struct
> > generic_pm_domain *genpd)
> > return ret;
> > }
> >
> > + dev_info(bc->dev, "%s: 3\n", __func__);
> > ret = pm_runtime_get_sync(bc->dev);
> > if (ret < 0) {
> > pm_runtime_put_noidle(bc->dev);
> > @@ -149,11 +152,15 @@ static int imx93_blk_ctrl_power_on(struct
> > generic_pm_domain *genpd)
> > goto disable_clk;
> > }
> >
> > + dev_info(bc->dev, "%s: 4\n", __func__);
> > +
> > /* ungate clk */
> > regmap_clear_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
> > + dev_info(bc->dev, "%s: 5\n", __func__);
> >
> > /* release reset */
> > regmap_set_bits(bc->regmap, BLK_SFT_RSTN, data->rst_mask);
> > + dev_info(bc->dev, "%s: 6\n", __func__);
> >
> > dev_dbg(bc->dev, "pd_on: name: %s\n", genpd->name);
> >
> >
> > ---8<---
> >
> > Best regards,
> > Alexander
> >
> > > Regards,
> > > Liu Ying
> > >
> > > > Best regards,
> > > > Alexander
> > > >
> > > > > v3->v4:
> > > > > * Improve warning message when ignoring invalid LCDIF OF
> > > > > endpoint ids
> > > > > in
> > > > >
> > > > > patch 5/6. (Alexander)
> > > > >
> > > > > * Use 'new_{c,p}state' instead of 'new_{crtc,plane}_state' in
> > > > > patch
> > > > > 3/6.
> > > > >
> > > > > (Alexander)
> > > > >
> > > > > * Simplify lcdif_crtc_reset() by calling
> > > > > lcdif_crtc_atomic_destroy_state()
> > > > >
> > > > > in patch 3/6. (Alexander)
> > > > >
> > > > > * Add '!crtc->state' check in
> > > > > lcdif_crtc_atomic_duplicate_state() in
> > > > > patch
> > > > > 3/6. (Alexander)
> > > > > * Collect Alexander's R-b tags on patch 1/6, 2/6 and 6/6.
> > > > >
> > > > > v2->v3:
> > > > > * Fix a trivial typo in patch 6/6's commit message.
> > > > >
> > > > > v1->v2:
> > > > > * Add Krzysztof's A-b and Marek's R-b tags on patch 1/6.
> > > > > * Split patch 2/2 in v1 into patch 2/6~6/6 in v2. (Marek,
> > > > > Alexander)
> > > > > * Drop '!remote ||' from lcdif_attach_bridge(). (Lothar)
> > > > > * Add comment on the 'base' member of lcdif_crtc_state
> > > > > structure to
> > > > >
> > > > > note it should always be the first member. (Lothar)
> > > > >
> > > > > * Drop unneeded 'bridges' member from lcdif_drm_private
> > > > > structure.
> > > > > * Drop a comment about bridge input bus format from
> > > > > lcdif_crtc_atomic_check().
> > > > >
> > > > > Liu Ying (6):
> > > > > dt-bindings: lcdif: Add i.MX93 LCDIF support
> > > > > drm: lcdif: Drop unnecessary NULL pointer check on lcdif-
> > > > > >bridge
> > > > > drm: lcdif: Determine bus format and flags in
> > > > > ->atomic_check()
> > > > > drm: lcdif: Check consistent bus format and flags across
> > > > > first
> > > > > bridges
> > > > > drm: lcdif: Add multiple encoders and first bridges support
> > > > > drm: lcdif: Add i.MX93 LCDIF compatible string
> > > > >
> > > > > .../bindings/display/fsl,lcdif.yaml | 7 +-
> > > > > drivers/gpu/drm/mxsfb/lcdif_drv.c | 71 ++++++-
> > > > > drivers/gpu/drm/mxsfb/lcdif_drv.h | 5 +-
> > > > > drivers/gpu/drm/mxsfb/lcdif_kms.c | 198
> > > > > ++++++++++++------
> > > > > 4 files changed, 206 insertions(+), 75 deletions(-)
>
>