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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 7B725C433E0 for ; Wed, 20 May 2020 13:48:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6442F207F9 for ; Wed, 20 May 2020 13:48:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726443AbgETNsc (ORCPT ); Wed, 20 May 2020 09:48:32 -0400 Received: from mail.baikalelectronics.com ([87.245.175.226]:59090 "EHLO mail.baikalelectronics.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726691AbgETNsc (ORCPT ); Wed, 20 May 2020 09:48:32 -0400 Received: from localhost (unknown [127.0.0.1]) by mail.baikalelectronics.ru (Postfix) with ESMTP id BE2DE8030875; Wed, 20 May 2020 13:48:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at baikalelectronics.ru Received: from mail.baikalelectronics.ru ([127.0.0.1]) by localhost (mail.baikalelectronics.ru [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 879XwsdEpqBa; Wed, 20 May 2020 16:48:28 +0300 (MSK) Date: Wed, 20 May 2020 16:48:26 +0300 From: Serge Semin To: Thomas Bogendoerfer CC: Serge Semin , Alexey Malahov , Paul Burton , Ralf Baechle , Greg Kroah-Hartman , Arnd Bergmann , Rob Herring , , , Vincenzo Frascino , Thomas Gleixner , , Subject: Re: [PATCH v2 18/20] mips: csrc-r4k: Decrease r4k-clocksource rating if CPU_FREQ enabled Message-ID: <20200520134826.pc6si3k6boaexp4i@mobilestation> References: <20200508154150.GB22247@alpha.franken.de> <20200511133121.cz5axbwynhmqkx7x@mobilestation> <20200515074827.6p5zx4sb3bmavjih@mobilestation> <20200515210647.GA22922@alpha.franken.de> <20200518134820.wedoumgbsllvhem6@mobilestation> <20200518163206.GA17800@alpha.franken.de> <20200518205752.txbylbjt2zkwdwwe@mobilestation> <20200519155053.GB15797@alpha.franken.de> <20200520121201.wohv6u646rx5otkf@mobilestation> <20200520133827.GA17714@alpha.franken.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20200520133827.GA17714@alpha.franken.de> X-ClientProxiedBy: MAIL.baikal.int (192.168.51.25) To mail (192.168.51.25) Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Wed, May 20, 2020 at 03:38:27PM +0200, Thomas Bogendoerfer wrote: > On Wed, May 20, 2020 at 03:12:01PM +0300, Serge Semin wrote: > > Since you don't like the way I initially fixed it, suppose there we don't have > > another way but to introduce something like CONFIG_MIPS_CPS_NS16550_WIDTH > > parameter to select a proper accessors, like sw in our case, and sb by defaul). > > Right? > > to be on the safe side it's probably the best thing. But I don't know > enough about CPS_NS16550 to judge whether shift value correlates with > possible access width. The base address passed to the _mips_cps_putc() leaf is UART-base address. It has nothing to do with CPS. See: /** * _mips_cps_putc() - write a character to the UART * @a0: ASCII character to write * @t9: UART base address */ LEAF(_mips_cps_putc) 1: lw t0, UART_LSR_OFS(t9) andi t0, t0, UART_LSR_TEMT beqz t0, 1b sb a0, UART_TX_OFS(t9) jr ra END(_mips_cps_putc) So it's base address must be accessed with proper alignment. On our case it's lw/sw instructions. Regarding using lw in the first line of the function. That's must be a bug, since further in the same function they use sb to access the UART Tx register. So reading a data from UART_LSR register should be also byte-sized by using lb. -Sergey > > Thomas. > > -- > Crap can work. Given enough thrust pigs will fly, but it's not necessarily a > good idea. [ RFC1925, 2.3 ]