Hello Tomasz, Laurent,

I have printed some logs during the dmabuf export and attach for the SGT 
issue below. Please find it in the attachment. I hope it will be useful.

Regards,
Subash

On 05/08/2012 04:45 PM, Subash Patel wrote:
> Hi Laurent,
>
> On 05/08/2012 02:44 PM, Laurent Pinchart wrote:
>> Hi Subash,
>>
>> On Monday 07 May 2012 20:08:25 Subash Patel wrote:
>>> Hello Thomasz, Laurent,
>>>
>>> I found an issue in the function vb2_dc_pages_to_sgt() below. I saw that
>>> during the attach, the size of the SGT and size requested mis-matched
>>> (by atleast 8k bytes). Hence I made a small correction to the code as
>>> below. I could then attach the importer properly.
>>
>> Thank you for the report.
>>
>> Could you print the content of the sglist (number of chunks and size
>> of each
>> chunk) before and after your modifications, as well as the values of
>> n_pages,
>> offset and size ?
> I will put back all the printk's and generate this. As of now, my setup
> has changed and will do this when I get sometime.
>>
>>> On 04/20/2012 08:15 PM, Tomasz Stanislawski wrote:
>>
>> [snip]
>>
>>>> +static struct sg_table *vb2_dc_pages_to_sgt(struct page **pages,
>>>> + unsigned int n_pages, unsigned long offset, unsigned long size)
>>>> +{
>>>> + struct sg_table *sgt;
>>>> + unsigned int chunks;
>>>> + unsigned int i;
>>>> + unsigned int cur_page;
>>>> + int ret;
>>>> + struct scatterlist *s;
>>>> +
>>>> + sgt = kzalloc(sizeof *sgt, GFP_KERNEL);
>>>> + if (!sgt)
>>>> + return ERR_PTR(-ENOMEM);
>>>> +
>>>> + /* compute number of chunks */
>>>> + chunks = 1;
>>>> + for (i = 1; i< n_pages; ++i)
>>>> + if (pages[i] != pages[i - 1] + 1)
>>>> + ++chunks;
>>>> +
>>>> + ret = sg_alloc_table(sgt, chunks, GFP_KERNEL);
>>>> + if (ret) {
>>>> + kfree(sgt);
>>>> + return ERR_PTR(-ENOMEM);
>>>> + }
>>>> +
>>>> + /* merging chunks and putting them into the scatterlist */
>>>> + cur_page = 0;
>>>> + for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
>>>> + unsigned long chunk_size;
>>>> + unsigned int j;
>>>
>>> size = PAGE_SIZE;
>>>
>>>> +
>>>> + for (j = cur_page + 1; j< n_pages; ++j)
>>>
>>> for (j = cur_page + 1; j< n_pages; ++j) {
>>>
>>>> + if (pages[j] != pages[j - 1] + 1)
>>>> + break;
>>>
>>> size += PAGE
>>> }
>>>
>>>> +
>>>> + chunk_size = ((j - cur_page)<< PAGE_SHIFT) - offset;
>>>> + sg_set_page(s, pages[cur_page], min(size, chunk_size), offset);
>>>
>>> [DELETE] size -= chunk_size;
>>>
>>>> + offset = 0;
>>>> + cur_page = j;
>>>> + }
>>>> +
>>>> + return sgt;
>>>> +}
>>
> Regards,
> Subash