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=-11.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 9267CC4741F for ; Mon, 9 Nov 2020 00:26:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 47F95206C0 for ; Mon, 9 Nov 2020 00:26:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fnarfbargle.com header.i=@fnarfbargle.com header.b="k3xWNIuv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728767AbgKIA0L (ORCPT ); Sun, 8 Nov 2020 19:26:11 -0500 Received: from ns3.fnarfbargle.com ([103.4.19.87]:59364 "EHLO ns3.fnarfbargle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727929AbgKIA0K (ORCPT ); Sun, 8 Nov 2020 19:26:10 -0500 Received: from srv.home ([10.8.0.1] ident=heh9363) by ns3.fnarfbargle.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84_2) (envelope-from ) id 1kbuzl-0001vH-Mx; Mon, 09 Nov 2020 08:25:17 +0800 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=fnarfbargle.com; s=mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To:Subject; bh=RIYcfOeKtFvzWTaNbBcRqZb/hFknofybHPd06UXh8aM=; b=k3xWNIuv59GZL5PeQhBg3cJaun4jEH/bOaFPk8bEIW+EUxi+TsrCwc0HKZwLTSvR2BIPTrNV+YJ0k1wRUYhzNuDBHUONRbNgTZV2mosr/pWEJ+HeEhEcEI6M4/sSWu3ek1IBPp5om2BdmyW5av/hcZesDoNaTuAsyZFUzIgPbNc=; Subject: Re: [PATCH v3] applesmc: Re-work SMC comms To: Guenter Roeck , Henrik Rydberg Cc: Arnd Bergmann , linux-hwmon@vger.kernel.org, "linux-kernel@vger.kernel.org" , hns@goldelico.com, Andreas Kemnade , Jean Delvare References: <70331f82-35a1-50bd-685d-0b06061dd213@fnarfbargle.com> <3c72ccc3-4de1-b5d0-423d-7b8c80991254@fnarfbargle.com> <6d071547-10ee-ca92-ec8b-4b5069d04501@bitmath.org> <8e117844-d62a-bcb1-398d-c59cc0d4b878@fnarfbargle.com> <9109d059-d9cb-7464-edba-3f42aa78ce92@bitmath.org> <5310c0ab-0f80-1f9e-8807-066223edae13@bitmath.org> <57057d07-d3a0-8713-8365-7b12ca222bae@fnarfbargle.com> <41909045-9486-78d9-76c2-73b99a901b83@bitmath.org> <20201108101429.GA28460@mars.bitmath.org> From: Brad Campbell Message-ID: Date: Mon, 9 Nov 2020 11:25:15 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/11/20 3:06 am, Guenter Roeck wrote: > On 11/8/20 2:14 AM, Henrik Rydberg wrote: >> On Sun, Nov 08, 2020 at 09:35:28AM +0100, Henrik Rydberg wrote: >>> Hi Brad, >>> >>> On 2020-11-08 02:00, Brad Campbell wrote: >>>> G'day Henrik, >>>> >>>> I noticed you'd also loosened up the requirement for SMC_STATUS_BUSY in read_smc(). I assume >>>> that causes problems on the early Macbook. This is revised on the one sent earlier. >>>> If you could test this on your Air1,1 it'd be appreciated. >>> >>> No, I managed to screw up the patch; you can see that I carefully added the >>> same treatment for the read argument, being unsure if the BUSY state would >>> remain during the AVAILABLE data phase. I can check that again, but >>> unfortunately the patch in this email shows the same problem. >>> >>> I think it may be worthwhile to rethink the behavior of wait_status() here. >>> If one machine shows no change after a certain status bit change, then >>> perhaps the others share that behavior, and we are waiting in vain. Just >>> imagine how many years of cpu that is, combined. ;-) >> >> Here is a modification along that line. >> > > Please resend this patch as stand-alone v4 patch. If sent like it was sent here, > it doesn't make it into patchwork, and is thus not only difficult to apply but > may get lost, and it is all but impossible to find and apply all tags. > Also, prior to Henrik's Signed=off-by: there should be a one-line explanation > of the changes made. G'day Guenter, Yes, I'll do that. I still have some more testing to do before it's pushed forwards. Regards, Brad > >> Compared to your latest version, this one has wait_status() return the >> actual status on success. Instead of waiting for BUSY, it waits for >> the other status bits, and checks BUSY afterwards. So as not to wait >> unneccesarily, the udelay() is placed together with the single >> outb(). The return value of send_byte_data() is augmented with >> -EAGAIN, which is then used in send_command() to create the resend >> loop. >> >> I reach 41 reads per second on the MBA1,1 with this version, which is >> getting close to the performance prior to the problems. >> >> >From b4405457f4ba07cff7b7e4f48c47668bee176a25 Mon Sep 17 00:00:00 2001 >> From: Brad Campbell >> Date: Sun, 8 Nov 2020 12:00:03 +1100 >> Subject: [PATCH] hwmon: (applesmc) Re-work SMC comms >> >> Commit fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()") >> introduced an issue whereby communication with the SMC became >> unreliable with write errors like : >> >> [ 120.378614] applesmc: send_byte(0x00, 0x0300) fail: 0x40 >> [ 120.378621] applesmc: LKSB: write data fail >> [ 120.512782] applesmc: send_byte(0x00, 0x0300) fail: 0x40 >> [ 120.512787] applesmc: LKSB: write data fail >> >> The original code appeared to be timing sensitive and was not reliable >> with the timing changes in the aforementioned commit. >> >> This patch re-factors the SMC communication to remove the timing >> dependencies and restore function with the changes previously >> committed. >> >> Tested on : MacbookAir6,2 MacBookPro11,1 iMac12,2, MacBookAir1,1, >> MacBookAir3,1 >> >> Fixes: fff2d0f701e6 ("hwmon: (applesmc) avoid overlong udelay()") >> Reported-by: Andreas Kemnade >> Tested-by: Andreas Kemnade # MacBookAir6,2 >> Acked-by: Arnd Bergmann >> Signed-off-by: Brad Campbell >> Signed-off-by: Henrik Rydberg >> >> --- >> Changelog : >> v1 : Inital attempt >> v2 : Address logic and coding style >> v3 : Removed some debug hangover. Added tested-by. Modifications for MacBookAir1,1 >> v4 : Do not expect busy state to appear without other state changes >> >> diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c >> index a18887990f4a..ea7c66d5788e 100644 >> --- a/drivers/hwmon/applesmc.c >> +++ b/drivers/hwmon/applesmc.c >> @@ -32,6 +32,7 @@ >> #include >> #include >> #include >> +#include >> >> /* data port used by Apple SMC */ >> #define APPLESMC_DATA_PORT 0x300 >> @@ -42,6 +43,11 @@ >> >> #define APPLESMC_MAX_DATA_LENGTH 32 >> >> +/* Apple SMC status bits */ >> +#define SMC_STATUS_AWAITING_DATA BIT(0) /* SMC has data waiting */ >> +#define SMC_STATUS_IB_CLOSED BIT(1) /* Will ignore any input */ >> +#define SMC_STATUS_BUSY BIT(2) /* Command in progress */ >> + >> /* wait up to 128 ms for a status change. */ >> #define APPLESMC_MIN_WAIT 0x0010 >> #define APPLESMC_RETRY_WAIT 0x0100 >> @@ -151,65 +157,78 @@ static unsigned int key_at_index; >> static struct workqueue_struct *applesmc_led_wq; >> >> /* >> - * wait_read - Wait for a byte to appear on SMC port. Callers must >> - * hold applesmc_lock. >> + * Wait for specific status bits with a mask on the SMC >> + * Used before and after writes, and before reads >> + * On success, returns the full status >> + * On failure, returns a negative error >> */ >> -static int wait_read(void) >> + >> +static int wait_status(u8 val, u8 mask) >> { >> unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC; >> u8 status; >> int us; >> >> for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { >> - usleep_range(us, us * 16); >> status = inb(APPLESMC_CMD_PORT); >> - /* read: wait for smc to settle */ >> - if (status & 0x01) >> - return 0; >> + if ((status & mask) == val) >> + return status; >> /* timeout: give up */ >> if (time_after(jiffies, end)) >> break; >> + usleep_range(us, us * 16); >> } >> - >> - pr_warn("wait_read() fail: 0x%02x\n", status); >> return -EIO; >> } >> >> /* >> - * send_byte - Write to SMC port, retrying when necessary. Callers >> + * send_byte_data - Write to SMC data port. Callers >> * must hold applesmc_lock. >> + * Parameter skip must be true on the last write of any >> + * command or it'll time out. >> */ >> -static int send_byte(u8 cmd, u16 port) >> + >> +static int send_byte_data(u8 cmd, u16 port, bool skip) >> { >> - u8 status; >> - int us; >> - unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC; >> + int status; >> >> + status = wait_status(0, SMC_STATUS_IB_CLOSED); >> + if (status < 0) >> + return status; >> outb(cmd, port); >> - for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) { >> - usleep_range(us, us * 16); >> - status = inb(APPLESMC_CMD_PORT); >> - /* write: wait for smc to settle */ >> - if (status & 0x02) >> - continue; >> - /* ready: cmd accepted, return */ >> - if (status & 0x04) >> - return 0; >> - /* timeout: give up */ >> - if (time_after(jiffies, end)) >> - break; >> - /* busy: long wait and resend */ >> - udelay(APPLESMC_RETRY_WAIT); >> - outb(cmd, port); >> - } >> + udelay(APPLESMC_MIN_WAIT); >> + status = wait_status(0, SMC_STATUS_IB_CLOSED); >> + if (status < 0) >> + return status; >> + if (skip || (status & SMC_STATUS_BUSY)) >> + return 0; >> + return -EAGAIN; >> +} >> >> - pr_warn("send_byte(0x%02x, 0x%04x) fail: 0x%02x\n", cmd, port, status); >> - return -EIO; >> +static int send_byte(u8 cmd, u16 port) >> +{ >> + return send_byte_data(cmd, port, false); >> } >> >> +/* >> + * send_command - Write a command to the SMC. Callers must hold applesmc_lock. >> + * If SMC is in undefined state, any new command write resets the state machine. >> + */ >> + >> static int send_command(u8 cmd) >> { >> - return send_byte(cmd, APPLESMC_CMD_PORT); >> + int ret; >> + int i; >> + >> + for (i = 0; i < 16; i++) { >> + ret = send_byte(cmd, APPLESMC_CMD_PORT); >> + if (!ret) >> + return ret; >> + if (ret != -EAGAIN) >> + break; >> + usleep_range(APPLESMC_MIN_WAIT, APPLESMC_MIN_WAIT * 16); >> + } >> + return -EIO; >> } >> >> static int send_argument(const char *key) >> @@ -239,7 +258,8 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len) >> } >> >> for (i = 0; i < len; i++) { >> - if (wait_read()) { >> + if (wait_status(SMC_STATUS_AWAITING_DATA, >> + SMC_STATUS_AWAITING_DATA | SMC_STATUS_IB_CLOSED) < 0) { >> pr_warn("%.4s: read data[%d] fail\n", key, i); >> return -EIO; >> } >> @@ -250,7 +270,7 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len) >> for (i = 0; i < 16; i++) { >> udelay(APPLESMC_MIN_WAIT); >> status = inb(APPLESMC_CMD_PORT); >> - if (!(status & 0x01)) >> + if (!(status & SMC_STATUS_AWAITING_DATA)) >> break; >> data = inb(APPLESMC_DATA_PORT); >> } >> @@ -275,7 +295,7 @@ static int write_smc(u8 cmd, const char *key, const u8 *buffer, u8 len) >> } >> >> for (i = 0; i < len; i++) { >> - if (send_byte(buffer[i], APPLESMC_DATA_PORT)) { >> + if (send_byte_data(buffer[i], APPLESMC_DATA_PORT, i == len - 1)) { >> pr_warn("%s: write data fail\n", key); >> return -EIO; >> } >> > >