Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934196AbaGXRXF (ORCPT ); Thu, 24 Jul 2014 13:23:05 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:51256 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752666AbaGXRXD (ORCPT ); Thu, 24 Jul 2014 13:23:03 -0400 Message-ID: <53D140EC.9020609@ti.com> Date: Thu, 24 Jul 2014 13:22:52 -0400 From: Santosh Shilimkar User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Jassi Brar , Linus Walleij CC: Grygorii Strashko , Suman Anna , Alexander Shiyan , Alexandre Courbot , "linux-gpio@vger.kernel.org" , , Muralidharan Karicheri , Rob Herring , Kumar Gala , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v1] gpio: keystone: add dsp gpio controller driver References: <1405507426-18992-1-git-send-email-grygorii.strashko@ti.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 24 July 2014 01:19 PM, Jassi Brar wrote: > On 23 July 2014 20:40, Linus Walleij wrote: >> On Wed, Jul 16, 2014 at 12:43 PM, Grygorii Strashko >> wrote: >> >>> From: Murali Karicheri >>> >>> On Keystone SOCs, ARM host can send interrupts to DSP cores using the >>> DSP GPIO controller IP. Each DSP GPIO controller provides 28 IRQ signals for >>> each DSP core. This is one of the component used by the IPC mechanism used >>> on Keystone SOCs. >>> >>> Keystone 2 DSP GPIO controller has specific features: >>> - each GPIO can be configured only as output pin; >>> - setting GPIO value to 1 causes IRQ generation on target DSP core; >>> - reading pin value returns 0 - if IRQ was handled or 1 - IRQ is still >>> pending. >>> >>> Signed-off-by: Murali Karicheri >>> Signed-off-by: Grygorii Strashko >> >> Pardon me. How is this GENERAL PURPOSE Input/Output? >> >> It seems very very much SPECIAL PURPOSE to me, it's like >> you're just shoehorning some IPC mechanism into the GPIO >> subsystem, and this may be because the datasheet calls it >> GPIO when it's not. >> >> What other stuff than DSP is connected to these lines, and is it >> really even external lines? Aren't these just polysilicon rails >> pretty much hammered to be used by the DSP and nothing else. >> >> What is the difference between this and a mailbox IRQ line >> and the kind of stuff handled by drivers/mailbox? >> >> I'd like Suman and Jassi to have a look at this to see if it's >> actually a mailbox before we proceed. >> > The controller seems like most others, only incapable of reading > signals (output only). > The userspace driving those signals to communicate with a DSP isn't > enough to call it a mailbox usecase, because on a different board the > userspace may drive those signals to control LEDs :) > Exactly !! And that was my point. Thanks for echo. Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/