From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: [PATCH 15/15] tty: serial: 8250: omap: add dma support Date: Fri, 29 Aug 2014 11:32:36 +0200 Message-ID: <540048B4.7010807@linutronix.de> References: <1408124563-31541-1-git-send-email-bigeasy@linutronix.de> <1408124563-31541-16-git-send-email-bigeasy@linutronix.de> <20140815210211.GD9239@atomide.com> <53F5AF0D.5060409@linutronix.de> <20140821184416.GF10066@atomide.com> <53FE3779.5090908@linutronix.de> <20140827202313.GF16006@atomide.com> <20140828082348.GA5413@linutronix.de> <20140828164645.GG16006@atomide.com> <53FF84DF.7080406@linutronix.de> <20140828225454.GM16006@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20140828225454.GM16006@atomide.com> Sender: linux-kernel-owner@vger.kernel.org To: Tony Lindgren Cc: balbi@ti.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Vinod Koul , Greg Kroah-Hartman , Paul Walmsley List-Id: linux-omap@vger.kernel.org On 08/29/2014 12:54 AM, Tony Lindgren wrote: > * Sebastian Andrzej Siewior [140828 12:37]: >> On 08/28/2014 06:46 PM, Tony Lindgren wrote: >>> >>> Sounds like there should be some way to clear that state.. I wonder >>> if omap-serial.c had something before it's DMA support was removed? >> >> Its DMA was removed? Like there was DMA support? >=20 > Yeah see commit 494574304711a333386e7dd5fd3ebbc3b7024994... Interesting. I've been browsing that file and checking other trees and never noticed that it was there at some point. I only saw the pieces which looked it was there. > OK thanks, I'm seeing the same issue as you. And the idlest registers > don't show any blockers. Looking at the errata docs, seems like > "Usage Note 2.7" in sprz318f.pdf says: >=20 > Details When configured for DMA operations using smartidle mode (SYS= C[4:3].IDLEMODE =3D > 0x2), the UART module will not acknowledge incoming idle requests. A= s a consequence, > it can prevent L4 from going to idle. > When there are additional expected transfers, the UART should be pla= ced in force-idle > mode. Ehm. So I haven't found an errata document for omap3630, there is nothing like that in that one I have for am335x or dra7. The document you mentioned is for AM3715. Interesting=85 > So I've added also Paul to Cc, he may have better suggestions for the > hwmod flags to use. The experimental patch below seems to allow idlin= g > for me, care to give it a try? Yep, this one works. And I see DMA transfers (for RX side) after the core hit idle so it seems to look good :) >=20 > Regards, >=20 > Tony Sebastian From mboxrd@z Thu Jan 1 00:00:00 1970 From: bigeasy@linutronix.de (Sebastian Andrzej Siewior) Date: Fri, 29 Aug 2014 11:32:36 +0200 Subject: [PATCH 15/15] tty: serial: 8250: omap: add dma support In-Reply-To: <20140828225454.GM16006@atomide.com> References: <1408124563-31541-1-git-send-email-bigeasy@linutronix.de> <1408124563-31541-16-git-send-email-bigeasy@linutronix.de> <20140815210211.GD9239@atomide.com> <53F5AF0D.5060409@linutronix.de> <20140821184416.GF10066@atomide.com> <53FE3779.5090908@linutronix.de> <20140827202313.GF16006@atomide.com> <20140828082348.GA5413@linutronix.de> <20140828164645.GG16006@atomide.com> <53FF84DF.7080406@linutronix.de> <20140828225454.GM16006@atomide.com> Message-ID: <540048B4.7010807@linutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 08/29/2014 12:54 AM, Tony Lindgren wrote: > * Sebastian Andrzej Siewior [140828 12:37]: >> On 08/28/2014 06:46 PM, Tony Lindgren wrote: >>> >>> Sounds like there should be some way to clear that state.. I wonder >>> if omap-serial.c had something before it's DMA support was removed? >> >> Its DMA was removed? Like there was DMA support? > > Yeah see commit 494574304711a333386e7dd5fd3ebbc3b7024994... Interesting. I've been browsing that file and checking other trees and never noticed that it was there at some point. I only saw the pieces which looked it was there. > OK thanks, I'm seeing the same issue as you. And the idlest registers > don't show any blockers. Looking at the errata docs, seems like > "Usage Note 2.7" in sprz318f.pdf says: > > Details When configured for DMA operations using smartidle mode (SYSC[4:3].IDLEMODE = > 0x2), the UART module will not acknowledge incoming idle requests. As a consequence, > it can prevent L4 from going to idle. > When there are additional expected transfers, the UART should be placed in force-idle > mode. Ehm. So I haven't found an errata document for omap3630, there is nothing like that in that one I have for am335x or dra7. The document you mentioned is for AM3715. Interesting? > So I've added also Paul to Cc, he may have better suggestions for the > hwmod flags to use. The experimental patch below seems to allow idling > for me, care to give it a try? Yep, this one works. And I see DMA transfers (for RX side) after the core hit idle so it seems to look good :) > > Regards, > > Tony Sebastian