linux-kernel - Re: [PATCH 0/3] dmaengine: Stear users towards dma_request_slave

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Message-ID: <20200205115906.GF2618@vkoul-mobl>
Date:   Wed, 5 Feb 2020 17:29:06 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        dmaengine <dmaengine@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH 0/3] dmaengine: Stear users towards
 dma_request_slave_chan()

On 05-02-20, 13:56, Peter Ujfalusi wrote:
> Hi Vinod,
> 
> On 05/02/2020 13.31, Vinod Koul wrote:
> >> Looking at the commit which added it and I still don't get the point.
> >> If any of the channel is in use then we should not allow the DMA driver
> >> to go away at all.
> > 
> > Not really, if the device is already gone, we cant do much about it. We
> > have to handle that gracefully rather than oopsing
> 
> Ah, I have not thought about that. True.
> 
> > The important part is that the device is gone. Think about a device on
> > PCI card which is yanked off or a USB device unplugged. Device is
> > already gone, you can't communicate with it anymore. So all we can do is
> > handle the condition and exit, hence the new method to let driver know.
> 
> But for most devices this is not applicable, I also wondered what should
> I do in order to silence the print. Just add an empty device_release?

I will send a patch removing this before we hit release :) so nothing to
be done unless you have a hotpluggable device then would be good to add this.

Thanks
-- 
~Vinod