From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vinod Koul Subject: Re: [PATCH V2 0/3] dmaengine: bcm2835: support dma channel 11 to 14 Date: Tue, 19 Apr 2016 21:03:20 +0530 Message-ID: <20160419153320.GT2274@localhost> References: <1460381349-14408-1-git-send-email-kernel@martin.sperl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1460381349-14408-1-git-send-email-kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org Cc: Rob Herring , Mark Rutland , Stephen Warren , Lee Jones , Eric Anholt , Russell King , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-rpi-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, dmaengine-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On Mon, Apr 11, 2016 at 01:29:06PM +0000, kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org wrote: > From: Martin Sperl > > Right now the dma engine officially supports dma channel 11 and 12. > But the use of dma channel 12 immediately stalls the system. > > The reason is that the interrupt assigned right now to dma channel 11 > is actually a shared interrupt for dma channels 11 to 12. > So whenever the dma channel 12, 13 or 14 is used, it triggers the interrupt > for dma 11 which only clears the interrupt flag for dma channel 11. > This results in the interrupt 11 is triggered all the time. > > On top the requesting dma channel12 (and the corresponding irq) triggers > an immeditate stall of the system, because for the 12th interrupt > any dma channel will trigger also this interrupt - even if the dma channel > is controlled by the firmware. > > As the description in the default device-tree is (for the above reasons) > wrong a new means had to get devised that allows correct representation > of the mapping between interrupts and dma channels. > > For this the existing (but unused) device-tree property "interrupt-names" > is used to define the mapping. > > Implementing shared interrupts is another necessity when using dma channel > 11 to 14, so it is a part of this patch. Applied, thanks -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html