On 12/13/2016 02:58 PM, Takashi Sakamoto wrote:
> On 2016年12月13日 22:23, Takashi Sakamoto wrote:
>> Hi Arnaud,
>>>> This table is invariant in lifetime of the storage object, as well.
>>>> Let's put into .rodata section, too.
>>>>
>>> This table is updated in hdmi_codec_cea_init_channel_alloc so can not be
>>> constant. In theory i could declare all field instead of computing some.
>>> But for lisibility, i would prefer to just declare ca_index and
>>> speakers allocation field in this table (i will declared both as const)
>>
>> You should pay enough attention to a case that one system has several
>> GPUs to which relevant GPU drivers register HDMI_CODEC_DRV_NAME platform
>> device. The 'static' modifier has an effect to keep just one storage
>> object, thus your code causes bugs in the case.
>
> Oops, the bug is unrelated to the static modifier. The modifier is for
> reference scope. I'll correct as the file local symbol has just one
> storage object.
>
> (I might be tired tonight...)
>
i understood in this way :-)
As 'ca_index' and "speakers" fiel are constants
the fields computed in hdmi_codec_cea_init_channel_alloc will
not change if the functions is called several time ( multi-instances).
but agree that it is not very clean, but this should work.
To avoid to compute several time, i can also add a test in
hdmi_codec_cea_init_channel_alloc to do it only one time (by testing
hdmi_codec_channel_alloc[0].channels), or perhaps better an atomic local
variable to avoid side effect for Multiprocessor archs.
Now the second approach is to define all the field. This indeeds a big
table (around 256 lines instead of 32 lines):
static const struct hdmi_codec_cea_spk_alloc hdmi_codec_channel_alloc[] = {
{
.ca_index = 0x00,
.speakers = { 0, 0, 0, 0, 0, 0, FR, FL } },
.channels = 2,
.spk_mask = FR | FL,
.spk_na_mask = 0x00,
},
{ /* 2.1 */
.ca_index = 0x01,
.speakers = { 0, 0, 0, 0, 0, LFE, FR, FL } },
.channels = 3,
.spk_mask = FR | FL | LFE,
.spk_na_mask = 0x00,
},
{ /* Dolby Surround */
.ca_index = 0x02,
.speakers = { 0, 0, 0, 0, FC, 0, FR, FL } },
.channels = 4,
.spk_mask = FR | FL | FC,
.spk_na_mask = BIT(2),
},
[...]
{
.ca_index = 0x1f,
.speakers = { FRC, FLC, RR, RL, FC, LFE, FR, FL } },
.channels = 8,
.spk_mask = FRC | FLC | RR | RL | FC | LFE | FR | FL,
.spk_na_mask = 0x0,
},
I would prefer the first one to save lines, but i can implement the
second one (or another one if you have an alternative to propose).
Regards
Arnaud
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