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

[Inki Dae]

> -----Original Message-----
> From: Joonyoung Shim [mailto:jy0922.shim at samsung.com]
> Sent: Wednesday, March 13, 2013 7:28 PM
> To: Inki Dae
> Cc: airlied at linux.ie; dri-devel at lists.freedesktop.org;
> kyungmin.park at samsung.com; sw0312.kim at samsung.com; 'YoungJun Cho'
> Subject: Re: [PATCH 3/7] drm/exynos: Fix G2D core mulfunctioning issue
> 
> On 03/13/2013 07:14 PM, Inki Dae wrote:
> >
> >> -----Original Message-----
> >> From: Joonyoung Shim [mailto:jy0922.shim at samsung.com]
> >> Sent: Wednesday, March 13, 2013 6:53 PM
> >> To: Inki Dae
> >> Cc: airlied at linux.ie; dri-devel at lists.freedesktop.org;
> >> kyungmin.park at samsung.com; sw0312.kim at samsung.com; YoungJun Cho
> >> Subject: Re: [PATCH 3/7] drm/exynos: Fix G2D core mulfunctioning issue
> >>
> >> 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.
> > Right, these two things(LIST HOLD command and GCF interrupt enabling)
> should
> > be pair.
> >
> >> 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.
> >>
> > Agree. How about this? If node->event isn't NULL then set GCF to INTEN
> > register in g2d_dma_start(). For this way, I already mentioned through
> > internal email thread.
> 
> No, Once set GCF, it is set on end. Who can clear it?
> 

Maybe you say that g2d_dma_start() is called by exec ioctl so the GCF bit
could be set by only last node.  For this, We need to look into dma-driven
command processing. Assume that two more command lists exist and they are
executed at once. Then we CAN NOT GET each node while dma operation because
the command lists of each node are executed by dma at once.

On other words, there is no way to enable GCF bit only in case that a
command list completion interrupt is needed because the need is from user
side.

So I think we need some policy for g2d driver. For example, if user wants to
get event to each node, all nodes from the user should be operated with GCF
bit otherwise without GCF bit.
 
Any other idea?

> >> 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;
> >