Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934179AbaGXRT7 (ORCPT ); Thu, 24 Jul 2014 13:19:59 -0400 Received: from mail-qg0-f43.google.com ([209.85.192.43]:62387 "EHLO mail-qg0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751375AbaGXRT5 (ORCPT ); Thu, 24 Jul 2014 13:19:57 -0400 MIME-Version: 1.0 In-Reply-To: References: <1405507426-18992-1-git-send-email-grygorii.strashko@ti.com> Date: Thu, 24 Jul 2014 22:49:56 +0530 Message-ID: Subject: Re: [PATCH v1] gpio: keystone: add dsp gpio controller driver From: Jassi Brar To: Linus Walleij Cc: Grygorii Strashko , Suman Anna , Alexander Shiyan , Santosh Shilimkar , Alexandre Courbot , "linux-gpio@vger.kernel.org" , ivan.khoronzhuk@ti.com, Muralidharan Karicheri , Rob Herring , Kumar Gala , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 :) Cheers, Jassi -- 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/