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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C0FDC4363D for ; Tue, 22 Sep 2020 05:36:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19ED123A9D for ; Tue, 22 Sep 2020 05:36:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728880AbgIVFgz (ORCPT ); Tue, 22 Sep 2020 01:36:55 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:42064 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726495AbgIVFgv (ORCPT ); Tue, 22 Sep 2020 01:36:51 -0400 Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 08M5MRpj016410; Tue, 22 Sep 2020 07:22:27 +0200 Date: Tue, 22 Sep 2020 07:22:27 +0200 From: Willy Tarreau To: poeschel@lemonage.de Cc: Miguel Ojeda Sandonis , open list Subject: Re: [PATCH v2 28/32] auxdisplay: hd44780: Remove clear_fast Message-ID: <20200922052227.GA16386@1wt.eu> References: <20191016082430.5955-1-poeschel@lemonage.de> <20200921144645.2061313-1-poeschel@lemonage.de> <20200921144645.2061313-29-poeschel@lemonage.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200921144645.2061313-29-poeschel@lemonage.de> User-Agent: Mutt/1.6.1 (2016-04-27) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Lars, On Mon, Sep 21, 2020 at 04:46:40PM +0200, poeschel@lemonage.de wrote: > From: Lars Poeschel > > We remove the hd44780_clear_fast (display) clear implementation. charlcd > will fall back to use hd44780_common_clear_display then, which is much > much faster. I might have got confused, but it looks to me like patches 27 and 28 basically undo patch 26: in 26 you moved code to hd44780 and wrote a fallback, just to later delete that code. I seem to remember that the reason for the clear_fast() implementation is that the default clear_display() is quite slow for small displays, compared to what can be achieved by just filling the display with spaces (in the order of tens of milliseconds vs hundreds of microseconds). But I could be mistaken given how old this is, so please take my comment with a grain of salt. Willy