From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurentiu Tudor Subject: Re: [RFC 0/2] iommu: arm-smmu: Add support for early direct mappings Date: Wed, 27 May 2020 12:06:51 +0300 Message-ID: References: <20191209150748.2471814-1-thierry.reding@gmail.com> <20200228025700.GA856087@builder> <20200514193249.GE279327@builder.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: John Stultz , Bjorn Andersson Cc: Robin Murphy , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Thierry Reding , linux-arm-msm , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Will Deacon , linux-arm-kernel List-Id: linux-tegra@vger.kernel.org On 5/26/2020 11:34 PM, John Stultz wrote: > On Thu, May 14, 2020 at 12:34 PM wrote: >> >> On Thu 27 Feb 18:57 PST 2020, Bjorn Andersson wrote: >> >> Rob, Will, we're reaching the point where upstream has enough >> functionality that this is becoming a critical issue for us. >> >> E.g. Lenovo Yoga C630 is lacking this and a single dts patch to boot >> mainline with display, GPU, WiFi and audio working and the story is >> similar on several devboards. >> >> As previously described, the only thing I want is the stream mapping >> related to the display controller in place, either with the CB with >> translation disabled or possibly with a way to specify the framebuffer >> region (although this turns out to mess things up in the display >> driver...) >> >> I did pick this up again recently and concluded that by omitting the >> streams for the USB controllers causes an instability issue seen on one >> of the controller to disappear. So I would prefer if we somehow could >> have a mechanism to only pick the display streams and the context >> allocation for this. >> >> >> Can you please share some pointers/insights/wishes for how we can >> conclude on this subject? > > Ping? I just wanted to follow up on this discussion as this small > series is crucial for booting mainline on the Dragonboard 845c > devboard. It would be really valuable to be able to get some solution > upstream so we can test mainline w/o adding additional patches. +1 There are also some NXP chips that depend on this. Also, I've submitted a v2 [1] a while back that tries to address the feedback on the initial implementation. [1] https://patchwork.ozlabs.org/project/linux-tegra/list/?series=164853 --- Best Regards, Laurentiu