From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751573AbdJXGSU (ORCPT ); Tue, 24 Oct 2017 02:18:20 -0400 Received: from fllnx210.ext.ti.com ([198.47.19.17]:53135 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751330AbdJXGSS (ORCPT ); Tue, 24 Oct 2017 02:18:18 -0400 Subject: Re: [PATCH v2] dwc: dra7xx: Print link state to console for debug To: Bjorn Helgaas , Faiz Abbas References: <1508417009-30869-1-git-send-email-faiz_abbas@ti.com> <20171020230952.GZ6332@bhelgaas-glaptop.roam.corp.google.com> <3692fbeb-bf8a-6de6-898b-551d899e9e55@ti.com> <20171023140411.GB9092@bhelgaas-glaptop.roam.corp.google.com> CC: , , , From: Kishon Vijay Abraham I Message-ID: <6a82ce2d-3feb-a6eb-d33d-b4b1e3f6b33b@ti.com> Date: Tue, 24 Oct 2017 11:48:13 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <20171023140411.GB9092@bhelgaas-glaptop.roam.corp.google.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Bjorn, On Monday 23 October 2017 07:34 PM, Bjorn Helgaas wrote: > On Mon, Oct 23, 2017 at 03:59:49PM +0530, Faiz Abbas wrote: >> On Saturday 21 October 2017 04:39 AM, Bjorn Helgaas wrote: >>> On Thu, Oct 19, 2017 at 06:13:29PM +0530, Faiz Abbas wrote: >>>> Enable support for printing the LTSSM link state for debugging PCI >>>> when link is down. >>>> >>>> Signed-off-by: Faiz Abbas >>>> --- >>>> v2: >>>> 1. Changed dev_err() to dev_dbg() >>>> 2. Changed static char array to static const char * const >>>> 3. format changes >>> >>> I'm not really sure how much debug help we want to carry around in the >>> mainline kernel. End users aren't going to use this; it seems like >>> more of a lab tool, and in situations like that you usually end up >>> carrying around some out-of-tree patches for a while anyway. But I >>> can probably be convinced either way. >> >> It'll be easier to support customers if they can tell us what the state >> of the link is by just changing the log level. We won't have to send a >> debug patch to the customer to find that out. > > That still sounds like a lab debug situation to me. Regular customers > do not debug things at the level of the link state. I'm not aware of > any other drivers that do this, so including this hints that this > driver/hardware is not very mature. > > Printing text certainly *looks* nice, but it adds a lot of code and > I'm not sure how much actual value they add. Just printing a hex > value might be more reliable in terms of communicating it accurately > back to you. E.g., it might be easier to lose the distinction between > DISABLED_ENTRY and DISABLED_IDLE than between 0x745f and 0x7463, > especially in a phone situation. > > Anyway, if Kishon acks this, I'll apply it. One nit: please do the > "link up" test once, e.g., IMHO both print text and the debug print itself helps to save developer effort. FWIW: Acked-by: Kishon Vijay Abraham I Thanks Kishon