Messages in this thread |  | | Date | Wed, 6 Apr 2022 16:43:15 +0200 | Subject | Re: [PATCH] drm/amdgpu: Senseless code and unnecessary memset | From | Christian König <> |
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Am 06.04.22 um 16:26 schrieb Jani Nikula: > On Tue, 05 Apr 2022, Christian König <christian.koenig@amd.com> wrote: >> Am 05.04.22 um 19:36 schrieb Grigory Vasilyev: >>> Using memset on local arrays before exiting the function is pointless. >>> Compilator will remove this code. Also for local arrays is preferable to >>> use {0} instead of memset. Mistakes are often made when working with >>> memset. >> Well actually memset is preferred when working with structures which are >> given to the hardware parser because {0} won't initialize paddings. > Not that I'd know anything that's going on here... but it sure seems > strange to me to be passing unpacked structures where the padding might > matter to a "hardware parser".
Well to me it is an absolute miracle why the heck compilers don't initialize paddings.
We had so many ups moments over the years and I really don't see why it should be more optimal to do this.
Anyway, the memset() is used intentionally here and I don't really want to change it. What we could do is removing the second superfluous memset and use sizeof() instead of hard coding the size.
Regards, Christian.
> > *shrug* > > > BR, > Jani. > > >> So please don't use {0} in any of the atom bios code. >> >> Regards, >> Christian. >> >>> Signed-off-by: Grigory Vasilyev <h0tc0d3@gmail.com> >>> --- >>> drivers/gpu/drm/amd/amdgpu/atom.c | 8 +------- >>> 1 file changed, 1 insertion(+), 7 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/atom.c b/drivers/gpu/drm/amd/amdgpu/atom.c >>> index be9d61bcb8ae..537e48fbbe6b 100644 >>> --- a/drivers/gpu/drm/amd/amdgpu/atom.c >>> +++ b/drivers/gpu/drm/amd/amdgpu/atom.c >>> @@ -1538,11 +1538,9 @@ struct atom_context *amdgpu_atom_parse(struct card_info *card, void *bios) >>> int amdgpu_atom_asic_init(struct atom_context *ctx) >>> { >>> int hwi = CU16(ctx->data_table + ATOM_DATA_FWI_PTR); >>> - uint32_t ps[16]; >>> + uint32_t ps[16] = {0}; >>> int ret; >>> >>> - memset(ps, 0, 64); >>> - >>> ps[0] = cpu_to_le32(CU32(hwi + ATOM_FWI_DEFSCLK_PTR)); >>> ps[1] = cpu_to_le32(CU32(hwi + ATOM_FWI_DEFMCLK_PTR)); >>> if (!ps[0] || !ps[1]) >>> @@ -1551,10 +1549,6 @@ int amdgpu_atom_asic_init(struct atom_context *ctx) >>> if (!CU16(ctx->cmd_table + 4 + 2 * ATOM_CMD_INIT)) >>> return 1; >>> ret = amdgpu_atom_execute_table(ctx, ATOM_CMD_INIT, ps); >>> - if (ret) >>> - return ret; >>> - >>> - memset(ps, 0, 64); >>> >>> return ret; >>> }
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