From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) (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 EFBED22CF12 for ; Mon, 13 Jan 2025 14:17:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736777845; cv=none; b=qNDlmntSzuk/HiMybFRS2zvciAHm15rg/TMaYhVG+XlQqEYsd3g9GYcTj7FZAus7dsxYzfCRSxVbh2tp1TQ5cyT53q0/DjjeVsttl9gTxXy55DSbHFU3k+OpUQjyGaNB0c6nHWky/MSRT3S2UZkxbLLGBWWO4ZXXybF3nlXDuZA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1736777845; c=relaxed/simple; bh=G5Pt0Sn0y+fwk/C27M3CSjvZ0EDb6hxD1srwH94jkJQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=uKKhTEun8c4uBUIckgo0kjT6EE4FQipwdCadvpl9Om+2FRo0hbgYYABLto05y0rDQpgdHL+PwcihDMvWd/17D206cVs3GbTEhVMw8ji5P75llaLXW6Pfn6qfk/fHrp6rkkeGv8TaMlTqNa7elLHZFFkxa6uexNwzdQWvQQZhO1w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=FICuoIxI; arc=none smtp.client-ip=192.198.163.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="FICuoIxI" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1736777844; x=1768313844; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=G5Pt0Sn0y+fwk/C27M3CSjvZ0EDb6hxD1srwH94jkJQ=; b=FICuoIxIXLX/NFQW+gKUzQnZIL5LdRGMXkp+oeFNNO7U4+2Vbgjukv/O uj4ItqpgJMCp6ggClstVrMmY7PXG+dUmWeU82GKrZuTbddep834sghscd X+sbXcN41gJhwjt5Gb8SoDehd7gZA0ndGhd56Pf3ZxVb0/JO13urkhw+4 FkofFA6kIZAirhejUqqF++TQIX1AwnpCCxwMaGGMZK8GMG3jREai7qO/4 5CuCVWS9YVMV9SjJ+z+mh+2JGrtycG/5YhDxfo8Gm3y/ACqG31druR2v5 uRHIwQhXT70ypVRH2Po1jO4F2mHm3TYwgWkswMgcfyPaRbQRx9t3bnRes A==; X-CSE-ConnectionGUID: BcvgjSgLRWGvwh9GdFRcew== X-CSE-MsgGUID: tCJM+E3OQMWN/L4L3CKY/Q== X-IronPort-AV: E=McAfee;i="6700,10204,11314"; a="47618398" X-IronPort-AV: E=Sophos;i="6.12,310,1728975600"; d="scan'208";a="47618398" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Jan 2025 06:17:23 -0800 X-CSE-ConnectionGUID: sVfbRnLlSweUqRZP6yGZ8w== X-CSE-MsgGUID: 9kH8JENDQtWQGOYwWy+R9g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,199,1725346800"; d="scan'208";a="109520269" Received: from unknown (HELO [10.237.72.199]) ([10.237.72.199]) by orviesa003.jf.intel.com with ESMTP; 13 Jan 2025 06:17:23 -0800 Message-ID: Date: Mon, 13 Jan 2025 16:18:19 +0200 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] usb: xhci: set page size to the xHCI-supported size To: =?UTF-8?Q?Micha=C5=82_Pecio?= Cc: Niklas Neronin , linux-usb@vger.kernel.org References: <20250108142822.649862-1-niklas.neronin@linux.intel.com> <20250108142822.649862-3-niklas.neronin@linux.intel.com> <0825d8a0-d2f7-49a1-b6a9-a65fc865e923@linux.intel.com> <20250113111612.5726c3f6@foxbook> Content-Language: en-US From: Mathias Nyman In-Reply-To: <20250113111612.5726c3f6@foxbook> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 13.1.2025 12.16, Michał Pecio wrote: > Hi, > > On Fri, 10 Jan 2025 14:35:50 +0200, Mathias Nyman wrote: >> On 8.1.2025 16.28, Niklas Neronin wrote: >>> + page_shift = readl(&xhci->op_regs->page_size) & >>> XHCI_PAGE_SIZE_MASK; >> >> Should we check that page_shift value makes sense here? > > Maybe it would make sense to validate it. Interpreting PAGESIZE wrong > is potentially dangerous, because the xHC will assume that scratchpad > buffers are of this size and it can write to them whatever it wants. > > Before the buggy ffs() patch 81720ec5320c, the driver used to pick the > lowest set bit or warn if all are zero, but then it still ignored the > calculated size and used 4K. > > I would probably be safer to use the highest bit, or just reject the > xHC if it sets multiple bits (5.4.3 says: "the supported page size", > not "a bitmask of supported sizes"). Checking that one, and only one bit is set sounds good. If so then use that. Otherwise print a warning and use 4k page size. This to avoid regression. I don't know why the page size was hardcoded to 4k originally even if we first do all the gymnastics to read it from hardware. But it was done for some reason. > > 0xffffffff looks like a brain dead chip and not going to work anyway. Reading 0xffffffff from a PCI device mmio registers is possible if host is suddenly PCI hotplug removed (some Intel Alpine Ridge xHC), or if I remember correctly also in PCI D3Cold power state. > >> We used to hardcode page_size to 4k, and don't really know if all xHC >> vendors have a sane op_regs->page_size value. > > FWIW, all of mine report 4K as per debugfs: > > /sys/kernel/debug/usb/xhci/0000:00:10.0/reg-op:PAGESIZE = 0x00000001 > /sys/kernel/debug/usb/xhci/0000:02:00.0/reg-op:PAGESIZE = 0x00000001 > ... > > 00:10.0 USB controller: Advanced Micro Devices, Inc. [AMD] FCH USB XHCI Controller (rev 20) > 02:00.0 USB controller: Advanced Micro Devices, Inc. [AMD] 300 Series Chipset USB 3.1 xHCI Controller (rev 02) > 06:00.0 USB controller: ASMedia Technology Inc. ASM1142 USB 3.1 Host Controller > 09:00.0 USB controller: Renesas Electronics Corp. uPD720202 USB 3.0 Host Controller (rev 02) > 0a:00.0 USB controller: Etron Technology, Inc. EJ168 USB 3.0 Host Controller (rev 01) > 0b:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 03) > 0c:00.0 USB controller: VIA Technologies, Inc. VL805/806 xHCI USB 3.0 Controller (rev 01) > > Also ASM1042 and ASM3142. > > And I have an NVIDIA Tegra board which runs some antique kernel and > doesn't warn, so PAGESIZE must at least be non-zero there. Thanks, good to know these hosts work fine. Thanks Mathias