From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 3CFF09444; Fri, 22 Dec 2023 06:10:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="kifCBQFZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51FF7C433C8; Fri, 22 Dec 2023 06:10:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1703225444; bh=xYXbxxhkYye8R6cZYemP7SDJUtXgX90hz1d089uRcew=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kifCBQFZFekLHT8JNYbslYBtOe6aSFNcJiM7CZBZsVv0qXs/AkQw5/pNqaV3R5jKI UGU1IEJS8So4qEC/2FprG046fMAbkcnv7IJy7MfXa6TTgWJUqr7IaFjS1RkU1UDV5t uZvCTa0J4ZxEZKrcofnINPeoFUC2oCKFQATy3t2s= Date: Fri, 22 Dec 2023 07:10:41 +0100 From: Greg Kroah-Hartman To: Prashanth K Cc: Thinh Nguyen , Mathias Nyman , linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v2 1/2] usb: dwc3: host: Set XHCI_SG_TRB_CACHE_SIZE_QUIRK Message-ID: <2023122212-stellar-handlebar-2f70@gregkh> References: <20231212112521.3774610-1-quic_prashk@quicinc.com> <20231212112521.3774610-2-quic_prashk@quicinc.com> <2023121518-uncharted-riddance-7c58@gregkh> <849d0ea9-d4f7-c568-968c-88835f64fadf@quicinc.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <849d0ea9-d4f7-c568-968c-88835f64fadf@quicinc.com> On Fri, Dec 22, 2023 at 11:29:01AM +0530, Prashanth K wrote: > On 15-12-23 06:12 pm, Greg Kroah-Hartman wrote: > > On Tue, Dec 12, 2023 at 04:55:20PM +0530, Prashanth K wrote: > > > Upstream commit bac1ec551434 ("usb: xhci: Set quirk for > > > XHCI_SG_TRB_CACHE_SIZE_QUIRK") introduced a new quirk in XHCI > > > which fixes XHC timeout, which was seen on synopsys XHCs while > > > using SG buffers. But the support for this quirk isn't present > > > in the DWC3 layer. > > > > > > We will encounter this XHCI timeout/hung issue if we run iperf > > > loopback tests using RTL8156 ethernet adaptor on DWC3 targets > > > with scatter-gather enabled. This gets resolved after enabling > > > the XHCI_SG_TRB_CACHE_SIZE_QUIRK. This patch enables it using > > > the xhci device property since its needed for DWC3 controller. > > > > > > In Synopsys DWC3 databook, > > > Table 9-3: xHCI Debug Capability Limitations > > > Chained TRBs greater than TRB cache size: The debug capability > > > driver must not create a multi-TRB TD that describes smaller > > > than a 1K packet that spreads across 8 or more TRBs on either > > > the IN TR or the OUT TR. > > > > > > Cc: > > > Signed-off-by: Prashanth K > > > > What commit id does this fix? > > > This doesn't fix any commit as such, but adds the support for > XHCI_SG_TRB_CACHE_SIZE_QUIRK (which is present in XHCI layer) to DWC3 layer. So this is a new feature? How does this fit into the stable kernel rules? > I have CC'ed stable kernel for this to be back-ported to older kernels > (#5.11). Why that specific kernel version and newer? Why not list it as documented? > > > > > --- > > > drivers/usb/dwc3/host.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c > > > index 61f57fe5bb78..31a496233d87 100644 > > > --- a/drivers/usb/dwc3/host.c > > > +++ b/drivers/usb/dwc3/host.c > > > @@ -89,6 +89,8 @@ int dwc3_host_init(struct dwc3 *dwc) > > > memset(props, 0, sizeof(struct property_entry) * ARRAY_SIZE(props)); > > > + props[prop_idx++] = PROPERTY_ENTRY_BOOL("xhci-sg-trb-cache-size-quirk"); > > > > And this is ok if the entry is not present? > > > We are intending to use this quirk for all the dwc3 based devices since the > DWC3 XHC needs it. So you do not have this quirk yet in the kernel tree? We can't take code without any in-tree users. > If the entry is not present then we will hit stall if > certain conditions aren't met (have mentioned the condition in commit text). When will the quirk be added? To what platforms? thanks, greg k-h