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From: Greg Kroah-Hartman <>
To: Christoph Hellwig <>
Cc: Maxime Chevallier <>,
	Gavin Li <>,
	Laurentiu Tudor <>,
	Minas Harutyunyan <>,
	Alan Stern <>,
	Geoff Levand <>,
	Michal Simek <>,
	Shawn Guo <>,
	Sascha Hauer <>,
	Pengutronix Kernel Team <>,
	Fabio Estevam <>,
	NXP Linux Team <>,
	Mathias Nyman <>, Bin Liu <>,,,,,,,
Subject: Re: next take at setting up a dma mask by default for platform devices v2
Date: Thu, 22 Aug 2019 10:11:08 -0700
Message-ID: <> (raw)
In-Reply-To: <>

On Fri, Aug 16, 2019 at 08:24:29AM +0200, Christoph Hellwig wrote:
> Hi all,
> this is another attempt to make sure the dma_mask pointer is always
> initialized for platform devices.  Not doing so lead to lots of
> boilerplate code, and makes platform devices different from all our
> major busses like PCI where we always set up a dma_mask.  In the long
> run this should also help to eventually make dma_mask a scalar value
> instead of a pointer and remove even more cruft.
> The bigger blocker for this last time was the fact that the usb
> subsystem uses the presence or lack of a dma_mask to check if the core
> should do dma mapping for the driver, which is highly unusual.  So we
> fix this first.  Note that this has some overlap with the pending
> desire to use the proper dma_mmap_coherent helper for mapping usb
> buffers.  The first two patches have already been queued up by Greg
> and are only included for completeness.

Note to everyone.  The first two patches in this series is already in

I've applied the rest of the series to my usb-next branch (with the 6th
patch landing there later today.)  They are scheduled to be merge to
Linus in 5.4-rc1.

Christoph, thanks so much for these cleanups.

greg k-h

      parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-16  6:24 Christoph Hellwig
2019-08-16  6:24 ` [PATCH 1/6] usb: don't create dma pools for HCDs with a localmem_pool Christoph Hellwig
2019-08-16  6:24 ` [PATCH 2/6] usb: add a hcd_uses_dma helper Christoph Hellwig
2019-08-16  6:24 ` [PATCH 3/6] usb: add a HCD_DMA flag instead of guestimating DMA capabilities Christoph Hellwig
2019-08-16  6:24 ` [PATCH 4/6] usb/max3421: remove the dummy {un,}map_urb_for_dma methods Christoph Hellwig
2019-08-16  6:24 ` [PATCH 5/6] dma-mapping: remove is_device_dma_capable Christoph Hellwig
2019-08-16  6:24 ` [PATCH 6/6] driver core: initialize a default DMA mask for platform device Christoph Hellwig
2019-08-16  7:39   ` Geert Uytterhoeven
2019-08-22 17:11 ` Greg Kroah-Hartman [this message]

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