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From: Takashi Iwai <>
To: Takashi Sakamoto <>
Subject: Re: [alsa-devel] [PATCH] ALSA: ctl: allow TLV read operation for callback type of element in locked case
Date: Mon, 23 Dec 2019 16:03:53 +0100
Message-ID: <> (raw)
In-Reply-To: <>

On Mon, 23 Dec 2019 10:33:47 +0100,
Takashi Sakamoto wrote:
> A design of ALSA control core allows applications to execute three
> operations for TLV feature; read, write and command. Furthermore, it
> allows driver developers to process the operations by two ways; allocated
> array or callback function. In the former, read operation is just allowed,
> thus developers uses the latter when device driver supports variety of
> models or the target model is expected to dynamically change information
> stored in TLV container.
> The core also allows applications to lock any element so that the other
> applications can't perform write operation to the element for element
> value and TLV information. When the element is locked, write and command
> operation for TLV information are prohibited as well as element value.
> Any read operation should be allowed in the case.
> At present, when an element has callback function for TLV information,
> TLV read operation returns EPERM if the element is locked. On the
> other hand, the read operation is success when an element has allocated
> array for TLV information. In both cases, read operation is success for
> element value expectedly.
> This commit fixes the bug. This change can be backported to v4.14
> kernel or later.

The patch looks good but your sign-off is missing...


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Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-23  9:33 Takashi Sakamoto
2019-12-23  9:42 ` Takashi Sakamoto
2019-12-23 15:03 ` Takashi Iwai [this message]
2019-12-24 10:02   ` Takashi Sakamoto
2019-12-24 14:31     ` Takashi Iwai
2019-12-24 12:56 ` Jaroslav Kysela

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