linux-kernel - Re: [PATCH v2] dma: imx-sdma: add 1ms delay to ensure SDMA channel is stopped

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Message-ID: <20170327052138.GG9308@localhost>
Date:   Mon, 27 Mar 2017 10:51:38 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     jiada_wang@...tor.com
Cc:     dan.j.williams@...el.com, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] dma: imx-sdma: add 1ms delay to ensure SDMA channel
 is stopped

On Thu, Mar 16, 2017 at 11:12:09PM -0700, jiada_wang@...tor.com wrote:
> From: Jiada Wang <jiada_wang@...tor.com>
> 
> sdma_disable_channel() cannot ensure dma is stopped to access
> module's FIFOs. There is chance SDMA core is running and accessing
> BD when disable of corresponding channel, this may cause sometimes
> even after call of .sdma_disable_channel(), SDMA core still be
> running and accessing module's FIFOs.
> 
> According to NXP R&D team a delay of one BD SDMA cost time (maximum
> is 1ms) should be added after disable of the channel bit, to ensure
> SDMA core has really been stopped after SDMA clients call
> .device_terminate_all.
> 
> This patch introduces adds a new function sdma_disable_channel_with_delay()
> which simply adds 1ms delay after call sdma_disable_channel(),
> and set it as .device_terminate_all.

Applied after fixing the subsystem name.


-- 
~Vinod