From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C29CC77B7D for ; Sat, 13 May 2023 23:08:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231465AbjEMXIY (ORCPT ); Sat, 13 May 2023 19:08:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42254 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229447AbjEMXIV (ORCPT ); Sat, 13 May 2023 19:08:21 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC8E826B6 for ; Sat, 13 May 2023 16:08:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Sender:Reply-To:Content-ID:Content-Description; bh=TjHGaJUHIwmLNfBiBtZv+iP/AFRHxIyXSIV7GUOs+zI=; b=dN+ICr/4RxuEUk8/Phal1CmN0+ /BgX/tHEsIlXbb1LbMRyUKHFqKbaUPG0P3ENvRTc8TCvx0pKEW9H4LTuy9YaJDxlXEFDjQGsxV0tC FJKCwGRqoHstc6bvPdbv1tn7Wdp+v1QAOC9Ji+D/autlh3LE6+sLl8ubl8Pis8DZ2F0br8KmvGZFz FVsSocPHokMAPPVJXMQ6gWk1c/mT0tOFT/xxG1BckwB6DQ8XzS+sABVIG/TCZCE22CouvdLsP4VMK n+lhatc+xJNgruDf0ipdkdlljNUgRsLq84hqt2a/hNzwaFaOpR+asWzd5jKDp5EJcvVNN+UIdgVJU 4VR2UxaA==; Received: from [2601:1c2:980:9ec0::2764] by bombadil.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1pxyLc-00G3JT-19; Sat, 13 May 2023 23:08:20 +0000 Message-ID: Date: Sat, 13 May 2023 16:08:19 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [RFC PATCH] powerpc: udbg: export udbg_putc Content-Language: en-US To: =?UTF-8?Q?Pali_Roh=c3=a1r?= Cc: linux-kernel@vger.kernel.org, Michael Ellerman , Nicholas Piggin , Christophe Leroy , linuxppc-dev@lists.ozlabs.org, Arnd Bergmann References: <20230513055804.23775-1-rdunlap@infradead.org> <20230513091358.pzlexqnff5ydhlzf@pali> <20230513230532.ojjf2xkmkx4v4zdo@pali> From: Randy Dunlap In-Reply-To: <20230513230532.ojjf2xkmkx4v4zdo@pali> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/13/23 16:05, Pali Rohár wrote: > On Saturday 13 May 2023 15:53:19 Randy Dunlap wrote: >> Hi Pali, >> >> On 5/13/23 02:13, Pali Rohár wrote: >>> On Friday 12 May 2023 22:58:04 Randy Dunlap wrote: >>>> In a randconfig with CONFIG_SERIAL_CPM=m and >>>> CONFIG_PPC_EARLY_DEBUG_CPM=y, there is a build error: >>>> ERROR: modpost: "udbg_putc" [drivers/tty/serial/cpm_uart/cpm_uart.ko] undefined! >>>> >>>> The build can be fixed by exporting "udbg_putc" in udbg.c. >>>> >>>> OTOH, maybe something like this is more appropriate in >>>> arch/powerpc/Kconfig.debug? >>>> >>>> config PPC_EARLY_DEBUG_CPM >>>> bool "Early serial debugging for Freescale CPM-based serial ports" >>>> - depends on SERIAL_CPM >>>> + depends on SERIAL_CPM=y >>>> >>>> Signed-off-by: Randy Dunlap >>>> Cc: Michael Ellerman >>>> Cc: Nicholas Piggin >>>> Cc: Christophe Leroy >>>> Cc: linuxppc-dev@lists.ozlabs.org >>>> Cc: Arnd Bergmann >>>> Cc: "Pali Rohár" >>>> --- >>>> arch/powerpc/kernel/udbg.c | 1 + >>>> 1 file changed, 1 insertion(+) >>>> >>>> diff -- a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c >>>> --- a/arch/powerpc/kernel/udbg.c >>>> +++ b/arch/powerpc/kernel/udbg.c >>>> @@ -14,6 +14,7 @@ >>>> #include >>>> >>>> void (*udbg_putc)(char c); >>>> +EXPORT_SYMBOL(udbg_putc); >>>> void (*udbg_flush)(void); >>>> int (*udbg_getc)(void); >>>> int (*udbg_getc_poll)(void); >>> >>> Hello! I do not think that it is a good idea to export udbg functions >>> for kernel modules. I have quickly looked at the cpm_uart driver file >> >> Sure, that was just a conversation starter. >> >>> drivers/tty/serial/cpm_uart/cpm_uart_core.c and it looks like that once >>> udbg from it is registered then there is no code for unregistering it. >>> So I have feeling that compiling cpm_uart driver as module should not be >>> allowed when CONFIG_SERIAL_CPM_CONSOLE is enabled, and early debug >>> should depend on CONFIG_CONSOLE_POLL || CONFIG_SERIAL_CPM_CONSOLE. >> >> The other change above also fixes the build error: (Option 2) >> >>>> config PPC_EARLY_DEBUG_CPM >>>> bool "Early serial debugging for Freescale CPM-based serial ports" >>>> - depends on SERIAL_CPM >>>> + depends on SERIAL_CPM=y >> >> >> Also, making SERIAL_CPM (cpm_uart driver) be restricted to not allow it >> as a module when SERIAL_CPM_CONSOLE is enabled [how does one express that >> in Kconfig language?] will cause a circular dependency since SERIAL_CPM_CONSOLE >> depends on SERIAL_CPM=y. It looks like you are suggesting reversing the >> dependencies. > > I see that SERIAL_CPM_CONSOLE has already "depends on SERIAL_CPM=y". > Am I right that this already disallow compiling cpm_uart driver as > module when SERIAL_CPM_CONSOLE is enabled? No, it just prevents SERIAL_CPM_CONSOLE from being set when SERIAL_CPM=m. >>> Any other opinion? >> >> Yes, please. Otherwise I prefer my option 2. >> >> -- >> ~Randy > > Option 2 looks like a better solution. Thanks. -- ~Randy