On 10/22/19 4:01 PM, Paul Kocialkowski wrote: > Hi, > > On Tue 22 Oct 19, 15:37, Hans Verkuil wrote: >> On 10/22/19 3:17 PM, Paul Kocialkowski wrote: >>> Hi again, >>> >>> On Tue 22 Oct 19, 14:40, Paul Kocialkowski wrote: >>>> Hi Mauro and thanks for the review, >>>> >>>> On Thu 17 Oct 19, 09:57, Mauro Carvalho Chehab wrote: >>>>> Em Fri, 27 Sep 2019 16:34:11 +0200 >>>>> Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> escreveu: >>>>> >>>>>> This introduces support for HEVC/H.265 to the Cedrus VPU driver, with >>>>>> both uni-directional and bi-directional prediction modes supported. >>>>>> >>>>>> Field-coded (interlaced) pictures, custom quantization matrices and >>>>>> 10-bit output are not supported at this point. >>>>>> >>>>>> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> >>>>>> --- >>>>> >>>>> ... >>>>> >>>>>> + unsigned int ctb_size_luma = >>>>>> + 1 << log2_max_luma_coding_block_size; >>>>> >>>>> Shifts like this is a little scary. "1" constant is signed. So, if >>>>> log2_max_luma_coding_block_size is 31, the above logic has undefined >>>>> behavior. Different archs and C compilers may handle it on different >>>>> ways. >>>> >>>> I wasn't aware that it was the case, thanks for bringing this to light! >>>> I'll make it 1UL then. >>>> >>>>>> +#define VE_DEC_H265_LOW_ADDR_PRIMARY_CHROMA(a) \ >>>>>> + (((a) << 24) & GENMASK(31, 24)) >>>>> >>>>> Same applies here and on other similar macros. You need to enforce >>>>> (a) to be unsigned, as otherwise the behavior is undefined. >>>>> >>>>> Btw, this is a recurrent pattern on this file. I would define a >>>>> macro, e. g. something like: >>>>> >>>>> #define MASK_BITS_AND_SHIFT(v, high, low) \ >>>>> ((UL(v) << low) & GENMASK(high, low)) >>>>> >>>>> And use it for all similar patterns here. >>>> >>>> Sounds good! I find that the reverse wording (SHIFT_AND_MASK_BITS) would be >>>> a bit more explicit since the shift happens prior to the mask. >>> >>> Apparently the UL(v) macro just appends UL to v in preprocessor, so it won't >>> work with anything else than direct integers. >>> >>> I'll replace it with a (unsigned long) cast, that seems to do the job. >> >> Shouldn't that be a (u32) cast? Since this is used with 32 bit registers? > > This would work for cedrus, but I think that what Mauro had in mind was to > migrate this macro to linux/bits.h, where everthing else (including GENMASK) > is apparently defined in terms of unsigned long and not types with explicit > numbers of bits. So I find it more consistent to go with unsigned long. > > In our case, 64-bit platforms that use cedrus would calculate the macro on > 64 bits and use it in 32-bit variables. Since we're never masking beyond the > lower 32 bits, I don't see how things could go wrong and the situation looks > fairly similar to the use of GENMASK in similar conditions. > > Does that sound right to you or am I missing something here? Ah, OK. Fair enough. Regards, Hans > > Cheers, > > Paul > >> Regards, >> >> Hans >> >>> >>> Cheers, >>> >>> Paul >>> >>>> Also we probably need to have parenthesis around "low", right? >>>> >>>>> The best would be to include such macro at linux/bits.h, although some >>>>> upstream discussion is required. >>>>> >>>>> So, for now, let's add it at this header file, but work upstream >>>>> to have it merged there. >>>> >>>> Understood, I'll include it in that header for now and send a separate patch >>>> for inclusion in linux/bits.h (apparently the preprocessor doesn't care about >>>> redefinitions so we can just remove the cedrus fashion once the common one is >>>> in). >>>> >>>> What do you think? >>>> >>>> Cheers, >>>> >>>> Paul >>> >>> >>> >> >
