RE: [EXT] Re: [v2 1/3] drm/arm/mali-dp: Add display QoS interface configuration for Mali DP500

[Wen He <wen.he_1@nxp.com>]

> -----Original Message-----
> From: Liviu Dudau <liviu.dudau@arm.com>
> Sent: 2019年9月5日 0:13
> To: Wen He <wen.he_1@nxp.com>
> Cc: dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org;
> brian.starkey@arm.com; airlied@linux.ie; daniel@ffwll.ch; Leo Li
> <leoyang.li@nxp.com>
> Subject: Re: [EXT] Re: [v2 1/3] drm/arm/mali-dp: Add display QoS interface
> configuration for Mali DP500
> 
> Caution: EXT Email
> 
> On Thu, Aug 15, 2019 at 11:14:17AM +0000, Wen He wrote:
> >
> >
> > > -----Original Message-----
> > > From: Liviu Dudau <liviu.dudau@arm.com>
> > > Sent: 2019年7月22日 17:33
> > > To: Wen He <wen.he_1@nxp.com>
> > > Cc: dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org;
> > > brian.starkey@arm.com; airlied@linux.ie; daniel@ffwll.ch; Leo Li
> > > <leoyang.li@nxp.com>
> > > Subject: Re: [EXT] Re: [v2 1/3] drm/arm/mali-dp: Add display QoS
> > > interface configuration for Mali DP500
> > >
> > > Caution: EXT Email
> > >
> > > On Mon, Jul 22, 2019 at 02:12:08AM +0000, Wen He wrote:
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Liviu Dudau <liviu.dudau@arm.com>
> > > > > Sent: 2019年7月19日 19:46
> > > > > To: Wen He <wen.he_1@nxp.com>
> > > > > Cc: dri-devel@lists.freedesktop.org;
> > > > > linux-kernel@vger.kernel.org; brian.starkey@arm.com;
> > > > > airlied@linux.ie; daniel@ffwll.ch; Leo Li <leoyang.li@nxp.com>
> > > > > Subject: [EXT] Re: [v2 1/3] drm/arm/mali-dp: Add display QoS
> > > > > interface configuration for Mali DP500
> > > > >
> > > > > Caution: EXT Email
> > > > >
> > > > > On Fri, Jul 19, 2019 at 05:54:45PM +0800, Wen He wrote:
> > > > > > Configure the display Quality of service (QoS) levels priority
> > > > > > if the optional property node "arm,malidp-aqros-value" is
> > > > > > defined in DTS
> > > file.
> > > > > >
> > > > > > QoS signaling using AQROS and AWQOS AXI interface signals, the
> > > > > > AQROS is driven from the "RQOS" register, so needed to program
> > > > > > the RQOS register to avoid the 4k resolution flicker issue on
> > > > > > the LS1028A
> > > platform.
> > > > > >
> > > > > > Signed-off-by: Wen He <wen.he_1@nxp.com>
> > > > > > ---
> > > > > > change in v2:
> > > > > >         - modify some content based on feedback from
> > > > > > maintainers
> > > > > >
> > > > > >  drivers/gpu/drm/arm/malidp_drv.c  |  6 ++++++
> > > > > >  drivers/gpu/drm/arm/malidp_hw.c   | 13 +++++++++++++
> > > > > >  drivers/gpu/drm/arm/malidp_hw.h   |  3 +++
> > > > > >  drivers/gpu/drm/arm/malidp_regs.h | 10 ++++++++++
> > > > > >  4 files changed, 32 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/gpu/drm/arm/malidp_drv.c
> > > > > > b/drivers/gpu/drm/arm/malidp_drv.c
> > > > > > index f25ec4382277..61c49a0668a7 100644
> > > > > > --- a/drivers/gpu/drm/arm/malidp_drv.c
> > > > > > +++ b/drivers/gpu/drm/arm/malidp_drv.c
> > > > > > @@ -818,6 +818,12 @@ static int malidp_bind(struct device
> > > > > > *dev)
> > > > > >
> > > > > >       malidp->core_id = version;
> > > > > >
> > > > > > +     ret = of_property_read_u32(dev->of_node,
> > > > > > +
> "arm,malidp-arqos-value",
> > > > > > +                                     &hwdev->arqos_value);
> > > > > > +     if (ret)
> > > > > > +             hwdev->arqos_value = 0x0;
> > > > >
> > > > > Is zero the default value that you want? I thought it was 0x00010001.
> > > >
> > > > Actually, the register default value always is 0x00010001(can be
> > > > found in RM
> > > document).
> > >
> > > Exactly, but with your code you are overwriting it to 0 if the DT
> > > doesn't have the arm,malidp-arqos-value property.
> > >
> > > >
> > > > >
> > > > > > +
> > > > > >       /* set the number of lines used for output of RGB data */
> > > > > >       ret = of_property_read_u8_array(dev->of_node,
> > > > > >
> > > > > > "arm,malidp-output-port-lines", diff --git
> > > > > > a/drivers/gpu/drm/arm/malidp_hw.c
> > > > > > b/drivers/gpu/drm/arm/malidp_hw.c index
> > > > > > 50af399d7f6f..323683b1e9f7
> > > > > > 100644
> > > > > > --- a/drivers/gpu/drm/arm/malidp_hw.c
> > > > > > +++ b/drivers/gpu/drm/arm/malidp_hw.c
> > > > > > @@ -374,6 +374,19 @@ static void malidp500_modeset(struct
> > > > > malidp_hw_device *hwdev, struct videomode *
> > > > > >               malidp_hw_setbits(hwdev,
> > > > > > MALIDP_DISP_FUNC_ILACED,
> > > > > MALIDP_DE_DISPLAY_FUNC);
> > > > > >       else
> > > > > >               malidp_hw_clearbits(hwdev,
> > > MALIDP_DISP_FUNC_ILACED,
> > > > > > MALIDP_DE_DISPLAY_FUNC);
> > > > > > +
> > > > > > +     /*
> > > > > > +      * Program the RQoS register to avoid 4k resolution flicker
> > > > > > +      * on the LS1028A.
> > > > > > +      */
> > > > > > +     if (hwdev->arqos_value) {
> > > > > > +             val = hwdev->arqos_value;
> > > > > > +
> > > > > > +             if (mode->pixelclock == 594000000)
> > > > >
> > > > > If I remember correctly, you declare the pixelclocks in the
> > > > > device tree, so I wonder if this is needed here. We should just
> > > > > set what value was in the DT regardless of the pixelclock, and
> > > > > then you manipulate the DT to choose one of your fixed
> > > > > resolutions and also set the
> > > QoS value.
> > > >
> > > > Yes, you remember correctly, but
> > > > 1. declare the pixelclocks in the device tree.
> > > > About this, I was hoping to discuss it with you. I want to
> > > > implement another patch that just declare 27MHz reference clock in
> > > > the device tree and add a fake clock subsystem to enable/display
> > > > prepare to set PLL. I
> > > am thinking what to do next.
> > > > As I remember, I sent out a patch that "Disable checking for
> > > > required pixel clock", I think should be cancel it.
> > > >
> > > > 2. declare the fixed resolutions list in DTS.
> > > > Yes, Although I put four resolutions for supported list in DTS
> > > > file, but this just a workaround that If not enable EDID OR EDID
> > > > is not available. Once EDID is enabled, these resolutions list
> > > > declare will be remove in DTS. so we can't use it as a condition to set the
> QoS value.
> > >
> > > 3. Actually enable the clock provider. I've had a look at the public
> > > documentation and it looks like the the pixelclock is provided by an
> > > IDT VersaClock 5 generator, for which there is a kernel driver. I've
> > > started playing with it but got pulled back by other more immediate tasks.
> > >
> > > Anyway, what I was trying to hint was that putting in the code the
> > > exact pixelclock value might not be the best thing. In my view,
> > > pixelclock reflects the need for a certain bandwidth, with is
> > > usually a product of output (number of
> > > pixels) and refresh frequency. I'm guessing going above 4k@60 will
> > > also trigger the flicker, but with your patch we will not react correctly.
> > >
> > > Best regards,
> > > Liviu
> > >
> >
> > Hmm.. I've already written the pixel clock provider driver of the LS1028A and
> upstreamed..
> > So more resolutions will be support on LS1028A.
> > Thank you for the comments that which made me determined to get this
> done.
> >
> > For this change, I would be remove this condition "if (mode->pixelclock ==
> 594000000)"
> > And apply this change for all resolutions on LS1028A.
> >
> > How do you think?
> 
> Hi Wen,
> 
> Sorry, I was away on sabbatical until now.
> 
> Not sure if I got your message right: do you want to apply the RQOS value
> regardless of the resolution (but only if defined to a non-zero value in the DTS)?
> If so, then I'm fine with that idea. Can you send a refreshed patch?
> 

Yes, but I add one condition (if pixel clock > 148.5Mhz) in here , I already send v3 patch to mail list, please review again, Thanks a lot. 

Best Regards,
Wen

> Best regards,
> Liviu
> 
> 
> >
> > Best Regards,
> > Wen
> > >
> > > >
> > > > Best Regards,
> > > > Wen
> > > >
> > > > >
> > > > > Best regards,
> > > > > Liviu
> > > > >
> > > > > > +                     malidp_hw_setbits(hwdev, val,
> > > > > MALIDP500_RQOS_QUALITY);
> > > > > > +             else
> > > > > > +                     malidp_hw_clearbits(hwdev, val,
> > > > > MALIDP500_RQOS_QUALITY);
> > > > > > +     }
> > > > > >  }
> > > > > >
> > > > > >  int malidp_format_get_bpp(u32 fmt) diff --git
> > > > > > a/drivers/gpu/drm/arm/malidp_hw.h
> > > > > > b/drivers/gpu/drm/arm/malidp_hw.h index
> > > 968a65eed371..e4c36bc90bda
> > > > > > 100644
> > > > > > --- a/drivers/gpu/drm/arm/malidp_hw.h
> > > > > > +++ b/drivers/gpu/drm/arm/malidp_hw.h
> > > > > > @@ -251,6 +251,9 @@ struct malidp_hw_device {
> > > > > >
> > > > > >       /* size of memory used for rotating layers, up to two
> > > > > > banks available
> > > > > */
> > > > > >       u32 rotation_memory[2];
> > > > > > +
> > > > > > +     /* priority level of RQOS register used for driven the
> > > > > > + ARQOS signal
> > > */
> > > > > > +     u32 arqos_value;
> > > > > >  };
> > > > > >
> > > > > >  static inline u32 malidp_hw_read(struct malidp_hw_device
> > > > > > *hwdev,
> > > > > > u32
> > > > > > reg) diff --git a/drivers/gpu/drm/arm/malidp_regs.h
> > > > > > b/drivers/gpu/drm/arm/malidp_regs.h
> > > > > > index 993031542fa1..514c50dcb74d 100644
> > > > > > --- a/drivers/gpu/drm/arm/malidp_regs.h
> > > > > > +++ b/drivers/gpu/drm/arm/malidp_regs.h
> > > > > > @@ -210,6 +210,16 @@
> > > > > >  #define MALIDP500_CONFIG_VALID               0x00f00
> > > > > >  #define MALIDP500_CONFIG_ID          0x00fd4
> > > > > >
> > > > > > +/*
> > > > > > + * The quality of service (QoS) register on the DP500. RQOS
> > > > > > +register values
> > > > > > + * are driven by the ARQOS signal, using AXI transacations,
> > > > > > +dependent on the
> > > > > > + * FIFO input level.
> > > > > > + * The RQOS register can also set QoS levels for:
> > > > > > + *    - RED_ARQOS   @ A 4-bit signal value for close to underflow
> > > > > conditions
> > > > > > + *    - GREEN_ARQOS @ A 4-bit signal value for normal conditions
> > > > > > + */
> > > > > > +#define MALIDP500_RQOS_QUALITY          0x00500
> > > > > > +
> > > > > >  /* register offsets and bits specific to DP550/DP650 */
> > > > > >  #define MALIDP550_ADDR_SPACE_SIZE    0x10000
> > > > > >  #define MALIDP550_DE_CONTROL         0x00010
> > > > > > --
> > > > > > 2.17.1
> > > > > >
> > > > >
> > > > > --
> > > > > ====================
> > > > > | I would like to |
> > > > > | fix the world,  |
> > > > > | but they're not |
> > > > > | giving me the   |
> > > > >  \ source code!  /
> > > > >   ---------------
> > > > >     ¯\_(ツ)_/¯
> > >
> > > --
> > > ====================
> > > | I would like to |
> > > | fix the world,  |
> > > | but they're not |
> > > | giving me the   |
> > >  \ source code!  /
> > >   ---------------
> > >     ¯\_(ツ)_/¯
> 
> --
> ====================
> | I would like to |
> | fix the world,  |
> | but they're not |
> | giving me the   |
>  \ source code!  /
>   ---------------
>     ¯\_(ツ)_/¯