linux-kernel - Re: [PATCH v2] dmaengine: dma-jz4780: Break descriptor chains on JZ4740

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Message-ID: <20190725132809.GW12733@vkoul-mobl.Dlink>
Date:   Thu, 25 Jul 2019 18:58:09 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Paul Burton <paul.burton@...s.com>, od@...c.me,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] dmaengine: dma-jz4780: Break descriptor chains on
 JZ4740

On 14-07-19, 17:55, Paul Cercueil wrote:
> The current driver works perfectly fine on every generation of the
> JZ47xx SoCs, except on the JZ4740.
> 
> There, when hardware descriptors are chained together (with the LINK
> bit set), the next descriptor isn't automatically fetched as it should -
> instead, an interrupt is raised, even if the TIE bit (Transfer Interrupt
> Enable) bit is cleared. When it happens, the DMA transfer seems to be
> stopped (it doesn't chain), and it's uncertain how many bytes have
> actually been transferred.
> 
> Until somebody smarter than me can figure out how to make chained
> descriptors work on the JZ4740, we now disable chained descriptors on
> that particular SoC.

Applied, thanks

-- 
~Vinod