linux-kernel - Re: [RESEND PATCH v2] dmaengine: ti: k3-udma: Add system suspend/resume support

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Message-ID: <ZCaUcFXeOLRemD7J@matsya>
Date:   Fri, 31 Mar 2023 13:36:08 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Vignesh Raghavendra <vigneshr@...com>
Cc:     Peter Ujfalusi <peter.ujfalusi@...il.com>,
        dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [RESEND PATCH v2] dmaengine: ti: k3-udma: Add system
 suspend/resume support

On 29-03-23, 21:23, Vignesh Raghavendra wrote:
> The K3 platforms configure the DMA resources with the
> help of the TI's System Firmware's Device Manager(DM)
> over TISCI. The group of DMA related Resource Manager[1]
> TISCI messages includes: INTA, RINGACC, UDMAP, and PSI-L.
> This configuration however, does not persist in the DM
> after leaving from Suspend-to-RAM state. We have to restore
> the DMA channel configuration over TISCI for all configured
> channels when returning from suspend.
> 
> The TISCI resource management calls for each DMA type (UDMA,
> PKTDMA, BCDMA) happen in device_free_chan_resources() and
> device_alloc_chan_resources(). In pm_suspend() we store
> the current udma_chan_config for channels that still have
> attached clients and call device_free_chan_resources().
> In pm_resume() restore the udma_channel_config from backup
> and call device_alloc_chan_resources() for those channels.
> 
> Drivers like CPSW that use k3-udma-glue already do their own
> DMA resource management so use the late system suspend/resume hooks.

Applied, thanks

-- 
~Vinod