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

[Joonyoung Shim <jy0922.shim@samsung.com>]

On 03/13/2013 07:14 PM, Inki Dae wrote:
>
>> -----Original Message-----
>> From: Joonyoung Shim [mailto:jy0922.shim@samsung.com]
>> Sent: Wednesday, March 13, 2013 6:53 PM
>> To: Inki Dae
>> Cc: airlied@linux.ie; dri-devel@lists.freedesktop.org;
>> kyungmin.park@samsung.com; sw0312.kim@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@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?

>> Thanks.
>>
>>> Signed-off-by: YoungJun Cho <yj44.cho@samsung.com>
>>> Signed-off-by: Inki Dae <inki.dae@samsung.com>
>>> Signed-off-by: Kyungmin Park <kyungmin.park@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;
>