Re: [PATCH] drm/ttm: Avoid conflicting reserve_memtype during ttm_tt_set_page_caching.

[Thomas Hellstrom <thellstrom@vmware.com>]

Francisco Jerez wrote:
> Sorry for bringing this up again with nothing new to say, but it's still
> a problem (on nouveau it usually triggers a slow CPU-based eviction
> fallback). Thomas: Are you OK with this patch?
>
>   

Sorry, I've missed this patch. So is the problem that the core kernel 
complains if you try to move directly from wc to uc? In that case it 
looks OK to me:

Acked-by: Thomas Hellstrom <thellstrom@vmware.com>


>   
>> Fixes errors like:
>>     
>>> reserve_ram_pages_type failed 0x15b7a000-0x15b7b000, track 0x8, req 0x10
>>>       
>> when a BO is moved between WC and UC areas.
>>
>> Reported-by: Xavier Chantry <shiningxc@gmail.com>
>> Signed-off-by: Francisco Jerez <currojerez@riseup.net>
>> ---
>>  drivers/gpu/drm/ttm/ttm_tt.c |   23 ++++++++++++++++-------
>>  1 files changed, 16 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
>> index 9c2b1cc..e2123af 100644
>> --- a/drivers/gpu/drm/ttm/ttm_tt.c
>> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
>> @@ -198,17 +198,26 @@ EXPORT_SYMBOL(ttm_tt_populate);
>>  static inline int ttm_tt_set_page_caching(struct page *p,
>>  					  enum ttm_caching_state c_state)
>>  {
>> +	int ret = 0;
>> +
>>  	if (PageHighMem(p))
>>  		return 0;
>>  
>> -	switch (c_state) {
>> -	case tt_cached:
>> -		return set_pages_wb(p, 1);
>> -	case tt_wc:
>> -	    return set_memory_wc((unsigned long) page_address(p), 1);
>> -	default:
>> -		return set_pages_uc(p, 1);
>> +	if (get_page_memtype(p) != -1) {
>> +		/* p isn't in the default caching state, set it to
>> +		 * writeback first to free its current memtype. */
>> +
>> +		ret = set_pages_wb(p, 1);
>> +		if (ret)
>> +			return ret;
>>  	}
>> +
>> +	if (c_state == tt_wc)
>> +		ret = set_memory_wc((unsigned long) page_address(p), 1);
>> +	else if (c_state == tt_uncached)
>> +		ret = set_pages_uc(p, 1);
>> +
>> +	return ret;
>>  }
>>  #else /* CONFIG_X86 */
>>  static inline int ttm_tt_set_page_caching(struct page *p,
>> -- 
>> 1.6.4.4
>>     


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