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From: Xincheng Zhang <zhangxincheng@ultrarisc.com>
To: Michal Pecio <michal.pecio@gmail.com>
Cc: Xincheng Zhang <zhangxincheng@ultrarisc.com>,
	 Mathias Nyman <mathias.nyman@intel.com>,
	 Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org,  linux-kernel@vger.kernel.org,
	Forest Crossman <cyrozap@gmail.com>
Subject: Re: [PATCH] usb: xhci-pci: Disable 64-bit DMA for VIA VL805
Date: Wed, 24 Jun 2026 13:26:14 +0800	[thread overview]
Message-ID: <178227877476.3699479.5394120322900121995.b4-reply@b4> (raw)
In-Reply-To: <20260623121847.53749028.michal.pecio@gmail.com>

Hi Michal,

On 2026-06-23 12:18 +0200, Michal Pecio wrote:
> But I don't like this abuse of the quirk. Firstly, it causes
> unnecessary bouncing on systems with >4GB RAM and no IOMMU.
> I found other drivers that use DMA_BIT_MASK(36) or even weirder
> numbers, so it seems that we too could request 64 gigs exactly
> with a bit of driver refactoring.

Thanks for the review. I totally agree that using `DMA_BIT_MASK(36)` is
a much better approach to avoid bounce buffers and register width issues. 

I will prepare a v2 patch with this refactoring. I'll wait a bit for
Forest's input on the ASMedia chips before sending it out, just in case 
we need to handle them together.

Thanks,
Xincheng



  reply	other threads:[~2026-06-24  5:26 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-23  7:32 Xincheng Zhang
2026-06-23 10:18 ` Michal Pecio
2026-06-24  5:26   ` Xincheng Zhang [this message]
2026-06-24  7:06   ` Xincheng Zhang
2026-06-25  0:04     ` Michal Pecio
2026-06-25  2:16       ` Xincheng Zhang
2026-06-25 17:18         ` Michal Pecio
2026-06-26  2:08           ` Xincheng Zhang
2026-06-26  8:06           ` David Laight
2026-06-26  8:57             ` Michal Pecio
2026-06-26 10:55               ` David Laight

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