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Date:   Tue, 7 Aug 2018 00:25:41 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Alan Stern <stern@rowland.harvard.edu>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] USB: OHCI: ohci-sm501: complete URBs in BH context
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On Mon, Aug 06, 2018 at 09:03:35AM -0700, Guenter Roeck wrote:
> Yes, I can confirm that the warning is gone in -next. Problem solved,
> except of course there are still the warnings about the missing
> coherent_dma_mask.
> 
> sm501-usb sm501-usb: SM501 OHCI
> sm501-usb sm501-usb: new USB bus registered, assigned bus number 1
> WARNING: CPU: 0 PID: 1 at ./include/linux/dma-mapping.h:516 ohci_init+0x194/0x2d8
> 
> Is that warning also not warranted for the given use case, or is
> the missing mask indeed necessary ? It is easy to add - see
> https://lore.kernel.org/patchwork/patch/971411/ - but I do wonder
> if that change is appropriate.

Yes, every driver using dma coherent functions should set a coherent
mask.