Hi Anitha,
On Tue, Jul 27, 2021 at 05:31:13PM -0700, Anitha Chrisanthus wrote:
> From: Edmund Dea <edmund.j.dea@xxxxxxxxx>
>
> 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@xxxxxxxxx>
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@xxxxxxxxxxxx>
