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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DB17C433FE for ; Mon, 1 Nov 2021 15:33:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 45B0860F58 for ; Mon, 1 Nov 2021 15:33:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232565AbhKAPfj (ORCPT ); Mon, 1 Nov 2021 11:35:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232618AbhKAPfh (ORCPT ); Mon, 1 Nov 2021 11:35:37 -0400 Received: from mail-lj1-x22c.google.com (mail-lj1-x22c.google.com [IPv6:2a00:1450:4864:20::22c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BD016C061764; Mon, 1 Nov 2021 08:33:03 -0700 (PDT) Received: by mail-lj1-x22c.google.com with SMTP id k22so8446477ljk.5; Mon, 01 Nov 2021 08:33:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Wqdz10Mm65EnzR0Kq/J40aB1E0ruzup8GrITfXt/gHw=; b=LMQCTDmKquUkDoRBW4/w9msneoKGEK4Sg97eheYEjNxBcgNXHAQ7Bz/bmZ/kzUVxmJ 9xie+NpSUTyz8kMsMVd7/sozTnS5HXErInextPkNRzdy4hTCy3Kr81jo0j1msNhuxOEh 43RT8zIeW+LOZ8DqTcDvWhE150LKBJbq4SPV92z3lH+dBG54kCVPzxqbDTWN/XV8xPok UMbMslC8camT4/3O7kf7uZKoWAjNhPIHLFpmey/cEv6Z/31uxk7+FO+JfvUXkV72VbWM kL6f3vcJlU/Umzb3pzGVWuEpWi0vsZGinoe01bFljRn2jrihzFDeFFHMgXJJkOkcieAv ce5g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Wqdz10Mm65EnzR0Kq/J40aB1E0ruzup8GrITfXt/gHw=; b=i6++8BbLVP+6tcozKi/z+EBP9omYhvo//zu6+L/Xt4ik9TD3m+4YZFTq+8VHjisi/y 9SZG4lfVEM2IoaK0CC3aUc5s5q34YYXxV2t0TtvvP+CAVC60X2lusNZYib44gI5ZEExa q+WgdAqzJDh3u/ZQdfvuyZnpc3r2W9c4PPz5ZJd/hjRotRjdKRqTVPZhUXTatYbzifVE Iz1tNqWgyHfUEUtWwl4ejc8YplrQFwF6GsHeoUADd4/CDyF8pKE0ZzVwlKYiLl7qxwxL XRG6j9FOT/wnfeH1V8MIVb/09VwFauaepoJ5tKeXv78T/cKlO1rZOEQVRfXUZQtlRths a6dQ== X-Gm-Message-State: AOAM533cw5P1ylGID9fvOlijBGa2WQ5JrihL1oDxmNdMhhBEpiteWXYO RPd9BB4RL9ekhtWvGKBde5kCPv3Mishrksbm89w= X-Google-Smtp-Source: ABdhPJwR4i9Q6F+HLALUGEx6B5XFNOtLBdNxGvh4qMQmH4ULwWfrWX8uMoQ1K4g1AowWLfCj1gCD2kXNerR4xOydnME= X-Received: by 2002:a05:651c:b07:: with SMTP id b7mr32549252ljr.166.1635780782030; Mon, 01 Nov 2021 08:33:02 -0700 (PDT) MIME-Version: 1.0 References: <20211029201402.428284-1-wander@redhat.com> In-Reply-To: From: Andy Shevchenko Date: Mon, 1 Nov 2021 17:32:12 +0200 Message-ID: Subject: Re: [PATCH] tty: serial: Use fifo in 8250 console driver To: Wander Costa Cc: wander@redhat.com, Greg Kroah-Hartman , Jiri Slaby , "Maciej W. Rozycki" , Johan Hovold , Andrew Jeffery , "open list:SERIAL DRIVERS" , open list Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 1, 2021 at 5:22 PM Wander Costa wrote: > Em s=C3=A1b., 30 de out. de 2021 04:41, Andy Shevchenko > escreveu: > > On Friday, October 29, 2021, wrote: ... > > I don't see any links. > > Oops, sorry about that. I must have accidentally deleted it while > editing the commit message. > Here it is https://github.com/walac/serial-console-test. > I will update the patch with the link. Thanks! ... > > On how many different UARTs have you tested this? Have you tested oops = and NMI contexts? > > > I only tested in a half dozen machines that I have available. I tried > it in panic, warnings, IRQ contexts, etc. Theoretically, this change > should not be affected by the context. Theoretically... > > > What I would like to say here is that the code is being used on zillion= s of different 8250 implementations here and I would be rather skeptical ab= out enabling the feature for everyone. > > > I did my homework and studied the 16550 datasheets, but yes, there is > always this risk. Maybe people more experienced with PC serial ports > than me might think the patch is not worth the risk of breaking some > unknown number of devices out there, and I am ok with that. It is a > valid point. Here is a translation of my comment to a roadmap. 1. Introduce yet another UART quirk or capability (see corresponding UART_CAP_* or UART_*_QUIRK definitions) 2. Add your patch conditionally based on the above 3. Enable it on UART(s) you _have tested_ --=20 With Best Regards, Andy Shevchenko