From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756251AbcFHIST (ORCPT ); Wed, 8 Jun 2016 04:18:19 -0400 Received: from eusmtp01.atmel.com ([212.144.249.243]:20042 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755916AbcFHISP (ORCPT ); Wed, 8 Jun 2016 04:18:15 -0400 Subject: Re: [PATCH] ARM: at91: debug: use DEBUG_UART_VIRT To: Alexandre Belloni , Boris Brezillon References: <1465313079-6307-1-git-send-email-alexandre.belloni@free-electrons.com> <5756ECC5.6020908@atmel.com> <20160607162301.GL3363@piout.net> <5757C67E.3000301@atmel.com> CC: , Russell King , Arnd Bergmann , From: Nicolas Ferre Organization: atmel Message-ID: <5757D4C2.8030805@atmel.com> Date: Wed, 8 Jun 2016 10:18:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <5757C67E.3000301@atmel.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.161.30.18] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 08/06/2016 09:17, Nicolas Ferre a écrit : > Le 07/06/2016 18:23, Alexandre Belloni a écrit : >> On 07/06/2016 at 17:48:21 +0200, Nicolas Ferre wrote : >>> Le 07/06/2016 17:24, Alexandre Belloni a écrit : >>>> AT91 still uses an offset (0x0100 0000) from the physical address to map >>>> the debug UART. This is unfortunate as for some platforms (sama5d3 and >>>> earlier), it ends up in the PCI zone and PCI is enabled in multi_v7. >>>> Switch to DEBUG_UART_VIRT to solve that. >>>> >>>> Tested on sama5d3 and 9g20. >>>> >>>> Signed-off-by: Alexandre Belloni >>> >>> People using their old defconfigs must pay attention to this change... >>> but it's true that it's a debug configuration anyway... >>> >> >> I really doubt people are letting DEBUG_LL enabled in a production >> kernel... >> >>>> diff --git a/arch/arm/include/debug/at91.S b/arch/arm/include/debug/at91.S >>>> index d4ae3b8e2426..0098401e5aeb 100644 >>>> --- a/arch/arm/include/debug/at91.S >>>> +++ b/arch/arm/include/debug/at91.S >>>> @@ -9,14 +9,6 @@ >>>> * >>>> */ >>>> >>>> -#ifdef CONFIG_MMU >>>> -#define AT91_IO_P2V(x) ((x) - 0x01000000) >>>> -#else >>>> -#define AT91_IO_P2V(x) (x) >>>> -#endif >>>> - >>>> -#define AT91_DEBUG_UART_VIRT AT91_IO_P2V(CONFIG_DEBUG_UART_PHYS) >>>> - >>>> #define AT91_DBGU_SR (0x14) /* Status Register */ >>>> #define AT91_DBGU_THR (0x1c) /* Transmitter Holding Register */ >>>> #define AT91_DBGU_TXRDY (1 << 1) /* Transmitter Ready */ >>>> @@ -24,7 +16,7 @@ >>>> >>>> .macro addruart, rp, rv, tmp >>>> ldr \rp, =CONFIG_DEBUG_UART_PHYS @ System peripherals (phys address) >>>> - ldr \rv, =AT91_DEBUG_UART_VIRT @ System peripherals (virt address) >>>> + ldr \rv, =CONFIG_DEBUG_UART_VIRT @ System peripherals (virt address) >>> >>> Shouldn't we protect the use of this defined value with some >>> #warning "Beware the value CONFIG_DEBUG_UART_VIRT haven't been defined: >>> is it intentional" >>> or even #error? >>> >>> or something like that? >>> >> >> Well, those that are using this feature are supposed to know what they >> are doing. There is now protection for CONFIG_DEBUG_UART_PHYS anyway. > > So, I know that developers are sensible people and know what they're > doing but still... what about having a protection for both anyway... > instead of silently crashing at runtime? After discussion with you on IRC, it seems to be not so easy to do and can harm the multi_v7 early debug facilities. So, for this patch: Acked-by: Nicolas Ferre It's true anyway that putting the proper values for these config options is not so easy (reading the help for CONFIG_DEBUG_AT91_UART)... And enhancing this situation if far beyond the scope of this patch. Thanks. Bye, -- Nicolas Ferre