linux-kernel - Re: [PATCH] media: atomisp: Use clamp_t() in ia_css_eed1_8_vmem

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Message-ID: <813ec28a-a88a-4ba1-976a-578fed314733@redhat.com>
Date: Fri, 6 Sep 2024 10:01:37 +0200
From: Hans de Goede <hdegoede@...hat.com>
To: David Laight <David.Laight@...LAB.COM>,
 'Mauro Carvalho Chehab' <mchehab+huawei@...nel.org>,
 Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
 Sakari Ailus <sakari.ailus@...ux.intel.com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>,
 "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
 "linux-staging@...ts.linux.dev" <linux-staging@...ts.linux.dev>
Subject: Re: [PATCH] media: atomisp: Use clamp_t() in
 ia_css_eed1_8_vmem_encode()

Hi David,

On 9/6/24 9:56 AM, David Laight wrote:
> From: Mauro Carvalho Chehab
>> Sent: 06 September 2024 07:16
>>
>> Em Sat, 27 Jul 2024 14:51:56 +0200
>> Christophe JAILLET <christophe.jaillet@...adoo.fr> escreveu:
>>
>>> Using clamp_t() instead of min_t(max_t()) is easier to read.
>>>
>>> It also reduces the size of the preprocessed files by ~ 193 ko.
>>> (see [1] for a discussion about it)
>>>
>>> $ ls -l ia_css_eed1_8.host*.i
>>>  4829993 27 juil. 14:36 ia_css_eed1_8.host.old.i
>>>  4636649 27 juil. 14:42 ia_css_eed1_8.host.new.i
>>>
>>> [1]: https://lore.kernel.org/all/23bdb6fc8d884ceebeb6e8b8653b8cfe@AcuMS.aculab.com/
>>>
>>> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
>>> ---
>>>  .../isp/kernels/eed1_8/ia_css_eed1_8.host.c   | 24 +++++++++----------
>>>  1 file changed, 12 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c
>> b/drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c
>>> index e4fc90f88e24..96c13ebc4331 100644
>>> --- a/drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c
>>> +++ b/drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c
>>> @@ -172,25 +172,25 @@ ia_css_eed1_8_vmem_encode(
>>>  		base = shuffle_block * i;
>>>
>>>  		for (j = 0; j < IA_CSS_NUMBER_OF_DEW_ENHANCE_SEGMENTS; j++) {
>>> -			to->e_dew_enh_x[0][base + j] = min_t(int, max_t(int,
>>> -							     from->dew_enhance_seg_x[j], 0),
>>> -							     8191);
>>> -			to->e_dew_enh_y[0][base + j] = min_t(int, max_t(int,
>>> -							     from->dew_enhance_seg_y[j], -8192),
>>> -							     8191);
>>> +			to->e_dew_enh_x[0][base + j] = clamp_t(int,
>>> +							       from->dew_enhance_seg_x[j],
>>> +							       0, 8191);
>>> +			to->e_dew_enh_y[0][base + j] = clamp_t(int,
>>> +							       from->dew_enhance_seg_y[j],
>>> +							       -8192, 8191);
>>
>> Such change introduces two warnings on smatch:
>>
>> drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c:
>> drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c:177
>> ia_css_eed1_8_vmem_encode() warn: assigning (-8192) to unsigned variable 'to->e_dew_enh_y[0][base +
>> j]'
>> drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c:
>> drivers/staging/media/atomisp/pci/isp/kernels/eed1_8/ia_css_eed1_8.host.c:182
>> ia_css_eed1_8_vmem_encode() warn: assigning (-8192) to unsigned variable 'to->e_dew_enh_a[0][base +
>> j]'
>>
>> Should dew_enhance_seg_x and dew_enhance_seg_y be converted to signed?
> 
> Someone clearly needs to read the code and work out what it is doing.

Ack, I'm looking into this now.

> First stage is to use clamp() (not clamp_t) to get warnings from the
> compiler for the RHS.

I already changed this to plain clamp() when merging it, that does not
cause any changes since the clamp-s are doing clamp(s32, -8192, 8192)

Regards,

Hans