From: "Benoît Thébaudeau" <benoit.thebaudeau@advansee.com>
To: James Courtier-Dutton <james.dutton@gmail.com>
Cc: alsa-devel@alsa-project.org, Clemens Ladisch <clemens@ladisch.de>
Subject: Re: [PATCH] alsa-lib/tlv: fix handling of raw value ranges
Date: Sat, 2 Jun 2012 14:26:02 +0200 (CEST) [thread overview]
Message-ID: <295179962.1878088.1338639962459.JavaMail.root@advansee.com> (raw)
In-Reply-To: <CAAMvbhGA=JUMH97V3OD_M2GZ=AqJfhUQMA6e8QXU2WLavzrvgg@mail.gmail.com>
Hi James,
On 2 June 2012 10:09, James Courtier-Dutton <james.dutton@gmail.com> wrote:
> In the userspace to kernel interface. A mixer control must have
> min/max values.
> When writing the value, all values within the range of min to max
> must
> be valid values.
> There are just too many user land tools that rely on this fact.
> Think of the use case or "Next step louder please". If the currently
> written value is 0x40, the current user land mixer apps would try to
> write 0x41, without even bothering to look at the dB tables.
> If you instead change the driver to map:
> 0x21 to 0x40 -> 0x00 to 0x1f
> 0x61 to 0xff -> 0x20 to 0xBE
> and set min to 0, and max to 0xbe
> The user space tools will then work fine.
>
> The dB conversion tables are just a friendly way of displaying a
> slightly more useful figure to the user than a percentage.
> If you have hardware with gaps like the above, the kernel driver will
> have to be fixed to remove the prohibited ranges in the kernel to
> userspace API.
> This sort of conversion is done in many other alsa kernel drivers.
Thanks for the details. I'll do that.
Regards,
Benoît
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prev parent reply other threads:[~2012-06-02 12:21 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <a995c693-9d0b-4572-af9c-85e3deebf37c@zose-store-12>
2012-03-29 23:05 ` [PATCH] alsa-lib/tlv: fix handling of raw value ranges Benoît Thébaudeau
2012-03-30 8:37 ` Clemens Ladisch
2012-03-30 10:41 ` Benoît Thébaudeau
2012-03-30 11:44 ` Takashi Iwai
2012-03-30 11:51 ` Takashi Iwai
2012-03-30 13:07 ` Benoît Thébaudeau
2012-03-30 13:23 ` Takashi Iwai
2012-03-30 12:38 ` Clemens Ladisch
2012-03-30 13:07 ` Benoît Thébaudeau
2012-03-30 13:10 ` Benoît Thébaudeau
2012-03-30 13:51 ` Clemens Ladisch
2012-03-30 13:58 ` Benoît Thébaudeau
2012-03-30 15:20 ` Benoît Thébaudeau
2012-03-30 15:45 ` Takashi Iwai
2012-03-30 15:59 ` Benoît Thébaudeau
2012-03-30 15:44 ` Takashi Iwai
2012-03-30 16:15 ` Benoît Thébaudeau
2012-05-21 19:38 ` Benoît Thébaudeau
2012-05-22 0:57 ` Takashi Iwai
2012-05-22 2:19 ` Benoît Thébaudeau
2012-05-22 8:45 ` Takashi Iwai
2012-05-22 16:06 ` Benoît Thébaudeau
2012-05-22 23:54 ` Takashi Iwai
2012-06-02 8:09 ` James Courtier-Dutton
2012-06-02 12:26 ` Benoît Thébaudeau [this message]
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