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 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 > >>>> --- > >>> > >>> ... > >>> > >>>> + 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? 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 > > > > > > > -- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com