[PATCH] media: rkisp1: uapi: change hist_bins array type from __u16 to __u32
Dafna Hirschfeld
dafna.hirschfeld at collabora.com
Tue Jan 19 12:47:01 EST 2021
Am 19.01.21 um 17:32 schrieb Hans Verkuil:
> On 19/01/2021 16:32, Dafna Hirschfeld wrote:
>>
>>
>> Am 19.01.21 um 16:00 schrieb Hans Verkuil:
>>> On 19/01/2021 15:53, Dafna Hirschfeld wrote:
>>>> Each entry in the array is a 20 bits value composed of 16
>>>> bits unsigned integer and 4 bits fractional part. So the
>>>> type should change to __u32.
>>>>
>>>> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld at collabora.com>
>>>> ---
>>>> This patch is applied on top of v6 of the patchset
>>>> "Fix the rkisp1 userspace API for later IP versions"
>>>>
>>>> include/uapi/linux/rkisp1-config.h | 5 +++--
>>>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/include/uapi/linux/rkisp1-config.h b/include/uapi/linux/rkisp1-config.h
>>>> index 57ca3eea985f..47f6b84d7c56 100644
>>>> --- a/include/uapi/linux/rkisp1-config.h
>>>> +++ b/include/uapi/linux/rkisp1-config.h
>>>> @@ -895,7 +895,8 @@ struct rkisp1_cif_isp_af_stat {
>>>> /**
>>>> * struct rkisp1_cif_isp_hist_stat - statistics histogram data
>>>> *
>>>> - * @hist_bins: measured bin counters
>>>> + * @hist_bins: measured bin counters. Each bin is a 20 bits value
>>>> + * composed of a 16-bit unsigned integer and 4 bits fractional part.
>>>
>>> So bits 0-3 are the fractional part and bits 4-19 contain the integer part?
>>> What goes where should be defined!
>>
>> Actually I don't know, I just copied the docs in the datasheet.
>> I can try figure it out. I can meanwhile send a patch without the doc until
>> we are sure. Is that OK?
>
> No, this should be documented properly.
I see that indeed bits 0-3 are the fractional part.
The measurements are taken over 25 sub-windows and it is possible to
give a weight to each window. If I set all weights to 1 then I expect to get
an integer value and indeed in that case I see that the last 4 bits are always 0.
If I set the weights to other than 1 I get the last 4 bits not only 0.
The UAPI is generally not very good documented mainly because there is currently
no open source userspace that uses it.
>
> Is this the only fractional type that is used in the rkisp1 uapi or are there
> others? (Just checking).
There are other places as well.
I see that there are some values in rkisp1_cif_isp_lsc_config that are fractional
and not documented.
The two other fractional types in the uapi are already documented.
I can add a patch that extends the documentation of all the fields in the uapi using the datasheet.
But I think such a patch can be added after de-staging.
Thanks,
Dafna
>
>>
>>>
>>> Looking at rkisp1_stats_get_hst_meas() I see this:
>>>
>>> for (i = 0; i < RKISP1_CIF_ISP_HIST_BIN_N_MAX; i++)
>>> pbuf->params.hist.hist_bins[i] =
>>> (u8)rkisp1_read(rkisp1,
>>> RKISP1_CIF_ISP_HIST_BIN_0 + i * 4);
>>>
>>> Here this is cast to a u8, so how does this work?
>>
>> This seems to be a bug. I see that this cast is introduced in v12 of the patch
>> "media: staging: rkisp1: add capture device for statistics".
>> This cast does not exist in any of the downstream versions.
>
> Clearly something that needs to be fixed as well.
>
> Regards,
>
> Hans
>
>>
>> Thanks,
>> Dafna
>>
>>>
>>> There is something fishy here...
>>>
>>> Regards,
>>>
>>> Hans
>>>
>>>> *
>>>> * The histogram values divided into 16 bins for V10/V11 and 32 bins
>>>> * for V12/V13. It is configured within the struct rkisp1_cif_isp_hst_config.
>>>> @@ -909,7 +910,7 @@ struct rkisp1_cif_isp_af_stat {
>>>> * RKISP1_CIF_ISP_HIST_BIN_N_MAX is equal to the maximum of the two.
>>>> */
>>>> struct rkisp1_cif_isp_hist_stat {
>>>> - __u16 hist_bins[RKISP1_CIF_ISP_HIST_BIN_N_MAX];
>>>> + __u32 hist_bins[RKISP1_CIF_ISP_HIST_BIN_N_MAX];
>>>> };
>>>>
>>>> /**
>>>>
>>>
>
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