From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 676E13C3453 for ; Fri, 10 Apr 2026 14:29:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775831391; cv=none; b=EcgxnFKs7y7qzf3zLYVe9i2iasQsp7vvkyMBgxQJF8YsaUkaryli3Yfpq8W5bTHy9PknRCgLMLD3l9H7rVZ5JGbBjWMuGSbxeH5IYpjZS4DvAsXuMKwoMJ1TIT0Y493e6yOS2I+n/pDespFSC8S6U89TtRWCTi3DQHPBQDIddjE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775831391; c=relaxed/simple; bh=NYFloXay/xXsehUJhCiOsl9WvUPlk0M6zs7gjSI6/fU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ulDAlsT67oHWSngj9rDDgtmeFpTkykVEpg0DV2T3JHCCJqpa2ISGoG0SqcwyuDL6ekRm11OraJ9vpnf2g7eS2kit7caKV9veGi75NpMxyf38hhUuw4FL2LvbpW+uOyvCpoqVbWozhuvJG72UhM6dbFURVJSEZk8NUmgrS3RG27o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=VL8wXUdQ; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=R4meZkh1; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="VL8wXUdQ"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="R4meZkh1" Received: from pps.filterd (m0279864.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 63AA5cGd1498620 for ; Fri, 10 Apr 2026 14:29:50 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= VDkUxqbhmmq0ZCCW/L+xCj4h3ekuGY++VyjKuMGZDIY=; b=VL8wXUdQ4po/Qnu3 IIyv9CggcnRfNQqgFbKKtZFdte3Lw/Qt7vA41FGJdr2HHvzN3f+/hDwI9usFptga JGv+NkyoHRSoat9CvniYRHDj4RB/uCdWNIUIS+2Vn0NHi8OScwE4/XYj5vECTx71 F267etcY4QOSxU5pJe06sRaLYXU1gaLASHJtJwigFaYL4nFi0omgdXb95XsR28Mg Hwlo8i3qb96t82LB+Hg4Srso1ZPNry4ijCxMzWrhUB5p//FlmqMuv6TzwUS5M2w0 Ab7Nai+HM+dORBYfwt7FDsVZnQz1uHOvCSOGeaEbSTIt2O0s5HCSdE3g0PSHQ7Th Znl2yQ== Received: from mail-qk1-f199.google.com (mail-qk1-f199.google.com [209.85.222.199]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4dey5b0rry-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Fri, 10 Apr 2026 14:29:49 +0000 (GMT) Received: by mail-qk1-f199.google.com with SMTP id af79cd13be357-8d1d81dad37so53883385a.3 for ; Fri, 10 Apr 2026 07:29:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1775831388; x=1776436188; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=VDkUxqbhmmq0ZCCW/L+xCj4h3ekuGY++VyjKuMGZDIY=; b=R4meZkh1hUFrleaqWseGO0N472zOwPYHDa4Q9hOsNlsHDkBiCxgg4jiOmSGmNntOn2 FZbtfy7jucX5IVVpM0aM1AsG2L+UOz/hwdvq5PVP1shN1Sn8WgqwKVOgYCOVjfUo57HQ 9m4rsGi386DOoGqRZBfgLJ1M110ZHFTHmkdaR8ZR7wUx8NLKVy3QUKPIPraLHA9nsUb3 Sjxx7sgvD2dT4dL2vyJzSWGUSHY4E/qOwGZpbo8nNJikxAIM0M2Qw67efhJBc098e/2Q L2lQvd90pIIqcA0vmRNSn+SwCZ7j2oO+tPjPGF0tNnxkOxx/l+2jlhUNC5pgy5eJYy1g qXdw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775831388; x=1776436188; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=VDkUxqbhmmq0ZCCW/L+xCj4h3ekuGY++VyjKuMGZDIY=; b=Mr3McVs+L/g5JdnfC3q6alirXO0z/458MaOJ3C9v1RwUHdbD9rSsasiuqckjjL/52u aIfsiHTMLywRwaunzX/OVMRJfvMOmdt/h9Y19ZrpaLk/HYbnWKIZQg686RDSGc5JmfZ1 ER5QReIBNdibelrFh2W1c6m29Vy0kIx1qD1f79e1sA1ogiOTHnY8/sonEHlogv6bB4HK /HrSzsL0l+wi/05wNk6NIgiWuWL6E+Mick/QkX+Q3qGWcRlcvKsutkYiya7ppg68Vq2n dA+6kEFLCU2mnxLR/Zlehuk8HD2iuOdpwXdzjK+6ks6jV3OXmQukxEIIpCt8Fk1n3MKH 0zsQ== X-Forwarded-Encrypted: i=1; AJvYcCXHwxGMJIXNuCJJOBAyesuvQxQbe6Lf2j0/pnRsoyGCudAafIsTleiLoT2dY/+pJT1OCx91EZ+xYMoquSE=@vger.kernel.org X-Gm-Message-State: AOJu0YzbY6of1I0aJI9xwd5mJRF8ZXxCnoNWi5bQpDGOpqydQl2n0k2d AycshXG/Cz0LxENFJgRP9xnhhed5RaGCvfGvhMdCXRrbIl7Plq+qnLjXkAx6DTTpi3tGLlV9b/X WWnSXka+c8dGiER0KG1N1Ym7hxsfdN7EG47uGjlKw01f/FML5EZHOin0kU4PLmrgTYgI= X-Gm-Gg: AeBDietMrCceWzpzrv+y2Kzu9BKUru4T93gWApxsrVbY7Ak8s2YJYJBecorQL2zmlGw zrSdQ8urZ21nrvbG7J/Q8uftdr53o+LBUE40sJ57m1NKVS8beQHbHVDnTsir7928VHsR+TuBaID zXRrY5yitRYBPXUQ7Qs915ob/++yrgGjkGbaGDocx5hvAX187Jbwtz8gFq/wFPxdAdKCyi6nasF XMQFaqWGN/176oHiGf4DvgTCUoh1c+kqes3bB397t7gFKWF/YP7q84JE2m9jnXXWa+UGT/9d1pz BQUSHt3QrWlPdW43F40yDJUC8Q0XSOFbHnkhyK3O7aqEudiCye2BnHMetHdvgiTN+PS3z5F/am7 HynanRcO3EUxovH8gGJKIjRmHDTq1uRhfOtcU6yS7jiW9nFZknXpG5JToSNpZodmMU3TXalIzop g2WNU= X-Received: by 2002:a05:620a:179e:b0:8d3:a311:9277 with SMTP id af79cd13be357-8ddcecbe10amr308021785a.3.1775831388090; Fri, 10 Apr 2026 07:29:48 -0700 (PDT) X-Received: by 2002:a05:620a:179e:b0:8d3:a311:9277 with SMTP id af79cd13be357-8ddcecbe10amr308017685a.3.1775831387548; Fri, 10 Apr 2026 07:29:47 -0700 (PDT) Received: from [192.168.119.254] (078088045245.garwolin.vectranet.pl. [78.88.45.245]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-670703f5b31sm621074a12.11.2026.04.10.07.29.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Apr 2026 07:29:46 -0700 (PDT) Message-ID: <7d65539f-ece6-4e7c-a13e-6b12920346fa@oss.qualcomm.com> Date: Fri, 10 Apr 2026 16:29:43 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] thunderbolt: debugfs: Don't stop reading SB registers if just one fails To: Mika Westerberg Cc: Konrad Dybcio , Andreas Noever , Mika Westerberg , Yehezkel Bernat , usb4-upstream@oss.qualcomm.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260409-topic-tbt_sb_debugfs-v1-1-131540e0cc2b@oss.qualcomm.com> <20260409120457.GH3552@black.igk.intel.com> <75c962d1-7ade-483b-bbc9-a6c6140fc0e9@oss.qualcomm.com> <20260409143203.GI3552@black.igk.intel.com> Content-Language: en-US From: Konrad Dybcio In-Reply-To: <20260409143203.GI3552@black.igk.intel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: UyKAUadIgvcfbhaVnrr6Tu2HLoh4yZNi X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDEwMDEzNSBTYWx0ZWRfXyE9yDamwi/rR sVww4Uzc/8ZjO9JMEfZdl2dtq3Ti/ogkByAs3KCZHr0Nw4WV9lLiUwfNqznoTZl6y3xw3t4a+TA QEb/h6RQr2nM6WAeB95diTes5oZuwIgfeukvT+zf8MCUF2X1gNem28/ubxdUjOOID1hE5R8hP+f i0vUKGiB57gPo+3n/05Mt/uMdInHInW4i0iwCPWxTVTmomSqLwCWjfae9JZMpZ71eGbLkyb6zA+ 3zrUEpK+GFUSsQSGbQ1WgwW/+T1Mw8Zcq35J2O460fOOsLrFX6kw5Hi7t516wpAr09joY6oD6Pi TcQZjT9WeuvqybcAZFXU8mCv4p+Ybegj+ivOXXLUKsLgUibZ0w7V1tLBEY9BBqjA60bXq3RAK/g 9OztB8pdos4m1fqlbE1801gGXe09ec0bRS51PtcPey6QUgOoHCLycHsSBoLP6eowUAC+EHRz44U j581Aq/FO1uVm4Aazeg== X-Proofpoint-GUID: UyKAUadIgvcfbhaVnrr6Tu2HLoh4yZNi X-Authority-Analysis: v=2.4 cv=VsgTxe2n c=1 sm=1 tr=0 ts=69d9095d cx=c_pps a=HLyN3IcIa5EE8TELMZ618Q==:117 a=FpWmc02/iXfjRdCD7H54yg==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=t5gs6XZINShnl3d-aGYA:9 a=QEXdDO2ut3YA:10 a=bTQJ7kPSJx9SKPbeHEYW:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-10_04,2026-04-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 adultscore=0 spamscore=0 suspectscore=0 clxscore=1015 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604100135 On 4/9/26 4:32 PM, Mika Westerberg wrote: > On Thu, Apr 09, 2026 at 02:59:22PM +0200, Konrad Dybcio wrote: >> On 4/9/26 2:04 PM, Mika Westerberg wrote: [...] >>> I assume you have tested this on a hardware that supports this too, right? >> >> Hardware that exposes that register this does not exercise the altered >> code path. > > Well it may happen now that previously we got -EIO from some other register > and we stopped there, now this changes and we actually continue reading so > this definitely should be tested. The only register before USB4_SB_GEN4_TXFFE that isn't in-spec for both retimers in v1.0 and v2.0 is USB4_SB_LRD_TUNING (0x07). The PS8830 interestingly reports all zeroes (not a bounce). The registers following USB4_SB_GEN4_TXFFE in the array are USB4_SB_VERSION and USB4_SB_DATA. The former is not accessed anywhere else in the code, at first glance. The latter is, during NVM r/w and in margining ops, which have definitely been in use for a long time. Plus both of them are the v1.0 spec. The USB4_SB_GEN4_TXFFE specifically isn't (the retimer supplement pdf lists it as Rsvd, the main spec pdf omits it in the SB register table), as it wasn't previously useful (since Gen4 came about in v2.0). I don't think there's an easy way to limit the reading of this register since the bit indicating Gen4 capability is in USB4_SB_LINK_CONF (0x0c), which is Rsvd on retimers regardless of the spec revision. A connected port could easily have higher/lower capabilities, too. So all in all, my understanding is that any bugs caused by this patch (which would have to be in the form of "reading a register causes a wrongful change in behavior") would really surface spec non-compliance from a retimer, which should be quirked out explicitly if that's the case. I only have hardware with various Parade retimers, none of which claim Gen4 support. Konrad