RE: [PATCH 01/14] drm/kmb: Enable LCD DMA for low TVDDCV

["Chrisanthus, Anitha" <anitha.chrisanthus@intel.com>]

Hi Sam,
Please help! I tried to push the first two patches to drm-misc-fixes using dim push, but it pushed other things too besides these patches. I am sorry, don't know what went wrong.

Anitha

> -----Original Message-----
> From: Sam Ravnborg <sam@ravnborg.org>
> Sent: Wednesday, July 28, 2021 12:05 AM
> To: Chrisanthus, Anitha <anitha.chrisanthus@intel.com>
> Cc: dri-devel@lists.freedesktop.org; Dea, Edmund J
> <edmund.j.dea@intel.com>
> Subject: Re: [PATCH 01/14] drm/kmb: Enable LCD DMA for low TVDDCV
> 
> Hi Anitha,
> On Tue, Jul 27, 2021 at 05:31:13PM -0700, Anitha Chrisanthus wrote:
> > From: Edmund Dea <edmund.j.dea@intel.com>
> >
> > There's an undocumented dependency between LCD layer enable bits [2-5]
> > and the AXI pipelined read enable bit [28] in the LCD_CONTROL register.
> > The proper order of operation is:
> >
> > 1) Clear AXI pipelined read enable bit
> > 2) Set LCD layers
> > 3) Set AXI pipelined read enable bit
> >
> > With this update, LCD can start DMA when TVDDCV is reduced down to
> 700mV.
> >
> > Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
> > Signed-off-by: Edmund Dea <edmund.j.dea@intel.com>
> Patch is missing your s-o-b.
> 
> > ---
> >  drivers/gpu/drm/kmb/kmb_drv.c   | 14 ++++++++++++++
> >  drivers/gpu/drm/kmb/kmb_plane.c | 15 +++++++++++++--
> >  2 files changed, 27 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/kmb/kmb_drv.c
> b/drivers/gpu/drm/kmb/kmb_drv.c
> > index 96ea1a2c11dd..c0b1c6f99249 100644
> > --- a/drivers/gpu/drm/kmb/kmb_drv.c
> > +++ b/drivers/gpu/drm/kmb/kmb_drv.c
> > @@ -203,6 +203,7 @@ static irqreturn_t handle_lcd_irq(struct drm_device
> *dev)
> >  	unsigned long status, val, val1;
> >  	int plane_id, dma0_state, dma1_state;
> >  	struct kmb_drm_private *kmb = to_kmb(dev);
> > +	u32 ctrl = 0;
> >
> >  	status = kmb_read_lcd(kmb, LCD_INT_STATUS);
> >
> > @@ -227,6 +228,19 @@ static irqreturn_t handle_lcd_irq(struct drm_device
> *dev)
> >  				kmb_clr_bitmask_lcd(kmb, LCD_CONTROL,
> >  						    kmb-
> >plane_status[plane_id].ctrl);
> >
> > +				ctrl = kmb_read_lcd(kmb, LCD_CONTROL);
> > +				if (!(ctrl & (LCD_CTRL_VL1_ENABLE |
> > +				    LCD_CTRL_VL2_ENABLE |
> > +				    LCD_CTRL_GL1_ENABLE |
> > +				    LCD_CTRL_GL2_ENABLE))) {
> > +					/* If no LCD layers are using DMA,
> > +					 * then disable DMA pipelined AXI read
> > +					 * transactions.
> > +					 */
> > +					kmb_clr_bitmask_lcd(kmb,
> LCD_CONTROL,
> > +
> LCD_CTRL_PIPELINE_DMA);
> > +				}
> > +
> This function could benefit from a few helper functions to avoid all the
> indent. But this is un-related to this patch.
> 
> >  				kmb->plane_status[plane_id].disable = false;
> >  			}
> >  		}
> > diff --git a/drivers/gpu/drm/kmb/kmb_plane.c
> b/drivers/gpu/drm/kmb/kmb_plane.c
> > index d5b6195856d1..2888dd5dcc2c 100644
> > --- a/drivers/gpu/drm/kmb/kmb_plane.c
> > +++ b/drivers/gpu/drm/kmb/kmb_plane.c
> > @@ -427,8 +427,14 @@ static void kmb_plane_atomic_update(struct
> drm_plane *plane,
> >
> >  	kmb_set_bitmask_lcd(kmb, LCD_CONTROL, ctrl);
> >
> > -	/* FIXME no doc on how to set output format,these values are
> > -	 * taken from the Myriadx tests
> > +	/* Enable pipeline AXI read transactions for the DMA
> > +	 * after setting graphics layers. This must be done
> > +	 * in a separate write cycle.
> > +	 */
> > +	kmb_set_bitmask_lcd(kmb, LCD_CONTROL,
> LCD_CTRL_PIPELINE_DMA);
> > +
> > +	/* FIXME no doc on how to set output format,these values are taken
>                                                     ^ add space
> > +	 * from the Myriadx tests
> >  	 */
> >  	out_format |= LCD_OUTF_FORMAT_RGB888;
> >
> > @@ -526,6 +532,11 @@ struct kmb_plane *kmb_plane_init(struct
> drm_device *drm)
> >  		plane->id = i;
> >  	}
> >
> > +	/* Disable pipeline AXI read transactions for the DMA
> > +	 * prior to setting graphics layers
> > +	 */
> > +	kmb_clr_bitmask_lcd(kmb, LCD_CONTROL,
> LCD_CTRL_PIPELINE_DMA);
> > +
> >  	return primary;
> >  cleanup:
> >  	drmm_kfree(drm, plane);
> 
> With the two nits fixed:
> Acked-by: Sam Ravnborg <sam@ravnborg.org>