linux-kernel - Re: [greybus-dev] [PATCH 3/3] [PATCH] staging: greybus: __u8 is sufficient for snd_ctl_elem_type_t and snd_ctl_elem_iface_t

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Date:   Sat, 26 Sep 2020 12:01:08 +0800
From:   Coiby Xu <coiby.xu@...il.com>
To:     Alex Elder <elder@...aro.org>
Cc:     David Laight <David.Laight@...lab.com>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "moderated list:SOUND" <alsa-devel@...a-project.org>,
        Alex Elder <elder@...nel.org>, Takashi Iwai <tiwai@...e.com>,
        Johan Hovold <johan@...nel.org>,
        "moderated list:GREYBUS SUBSYSTEM" <greybus-dev@...ts.linaro.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [greybus-dev] [PATCH 3/3] [PATCH] staging: greybus: __u8 is
 sufficient for snd_ctl_elem_type_t and snd_ctl_elem_iface_t

On Fri, Sep 25, 2020 at 11:02:23AM -0500, Alex Elder wrote:
>On 9/25/20 9:11 AM, Coiby Xu wrote:
>>On Thu, Sep 24, 2020 at 10:54:50AM +0000, David Laight wrote:
>>>From: Coiby Xu
>>>>Sent: 24 September 2020 11:21
>>>>Use __8 to replace int and remove the unnecessary __bitwise type
>>>>attribute.
>>>>
>>>>Found by sparse,
>>>...
>>>>diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
>>>>index 535a7229e1d9..8e71a95644ab 100644
>>>>--- a/include/uapi/sound/asound.h
>>>>+++ b/include/uapi/sound/asound.h
>>>>@@ -950,7 +950,7 @@ struct snd_ctl_card_info {
>>>>     unsigned char components[128];    /* card components / fine
>>>>identification, delimited with one
>>>>space (AC97 etc..) */
>>>> };
>>>>
>>>>-typedef int __bitwise snd_ctl_elem_type_t;
>>>>+typedef __u8 snd_ctl_elem_type_t;
>>>> #define    SNDRV_CTL_ELEM_TYPE_NONE    ((__force
>>>>snd_ctl_elem_type_t) 0) /* invalid */
>>>> #define    SNDRV_CTL_ELEM_TYPE_BOOLEAN    ((__force
>>>>snd_ctl_elem_type_t) 1) /* boolean type */
>>>> #define    SNDRV_CTL_ELEM_TYPE_INTEGER    ((__force
>>>>snd_ctl_elem_type_t) 2) /* integer type */
>>>
>>>WTF is all that about anyway??
>>>What is wrong with:
>>>#define    SNDRV_CTL_ELEM_TYPE_NONE    0u /* invalid */
>>
>>I'm sorry I don't quite understand you. Are you suggesting
>>SNDRV_CTL_ELEM_TYPE_NONE
>>isn't needed in the first place?
>
>I think David is asking why it's defined the way it is,
>and I'd guess it's to have the compiler issue an error
>if you attempt to assign one of these values to a variable
>or field of the wrong type.
>
>No, you should not attempt to change this.

Thank you for the explanation!

>
>					-Alex
>>>    David
>>>
>>>-
>>>Registered Address Lakeside, Bramley Road, Mount Farm, Milton
>>>Keynes, MK1 1PT, UK
>>>Registration No: 1397386 (Wales)
>>>
>>
>>--
>>Best regards,
>>Coiby
>>_______________________________________________
>>greybus-dev mailing list
>>greybus-dev@...ts.linaro.org
>>https://lists.linaro.org/mailman/listinfo/greybus-dev
>

--
Best regards,
Coiby

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