[PATCH 3/7] drm/exynos: Fix G2D core mulfunctioning issue

[Joonyoung Shim]

On 03/13/2013 06:04 PM, Inki Dae wrote:
> From: YoungJun Cho <yj44.cho at samsung.com>
>
> This patch fixes G2D core mulfunctioning issue once g2d dma is started.
> Without 'DMA_HOLD_CMD_REG' register setting, there is only one interrupt
> after the execution to all command lists have been completed. And that
> induces watchdog. So this patch sets 'LIST_HOLD' command to the register
> so that command execution interrupt can be occured whenever each command
> list execution is finished.

No, this problem occurs as GCF bit of INTEN_REG register is enabled
always. If wants to raise interrupt immediately after a command list
finished, GCF bit should be enabled, and it also needs to enable of LIST
Hold bit of DMA_HOLD_CMD_REG register. If one of the two is missed out,
g2d hardware will not work normally sometimes.

This patch is just workaround and it can happen performance issue
because g2d hardware stops a moment whenever a command list finished.

So, we need the way which enable GCF bit only when a command list
completion interrupt needs.

Thanks.

> Signed-off-by: YoungJun Cho <yj44.cho at samsung.com>
> Signed-off-by: Inki Dae <inki.dae at samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
> ---
>   drivers/gpu/drm/exynos/exynos_drm_g2d.c |   13 ++++++++-----
>   1 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> index 095520f..91bc4cc 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
> @@ -82,7 +82,7 @@
>   #define G2D_DMA_LIST_DONE_COUNT_OFFSET	17
>   
>   /* G2D_DMA_HOLD_CMD */
> -#define G2D_USET_HOLD			(1 << 2)
> +#define G2D_USER_HOLD			(1 << 2)
>   #define G2D_LIST_HOLD			(1 << 1)
>   #define G2D_BITBLT_HOLD			(1 << 0)
>   
> @@ -863,10 +863,13 @@ int exynos_g2d_set_cmdlist_ioctl(struct drm_device *drm_dev, void *data,
>   	cmdlist->data[cmdlist->last++] = G2D_SRC_BASE_ADDR;
>   	cmdlist->data[cmdlist->last++] = 0;
>   
> -	if (node->event) {
> -		cmdlist->data[cmdlist->last++] = G2D_DMA_HOLD_CMD;
> -		cmdlist->data[cmdlist->last++] = G2D_LIST_HOLD;
> -	}
> +	/*
> +	 * 'LIST_HOLD' command should be set to the DMA_HOLD_CMD_REG
> +	 * if user wants G2D interrupt event once each command list or
> +	 * BitBLT command execution is finished.
> +	 */
> +	cmdlist->data[cmdlist->last++] = G2D_DMA_HOLD_CMD;
> +	cmdlist->data[cmdlist->last++] = G2D_LIST_HOLD;
>   
>   	/* Check size of cmdlist: last 2 is about G2D_BITBLT_START */
>   	size = cmdlist->last + req->cmd_nr * 2 + req->cmd_buf_nr * 2 + 2;