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Cc:     baolu.lu@linux.intel.com, Joerg Roedel <joro@8bytes.org>,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: No video output on 4.19-rc1 on Dell XPS 13 9360
To:     Dmitrii Tcvetkov <demfloro@demfloro.ru>
References: <20180908165747.16c2843c@fire.localdomain>
From:   Lu Baolu <baolu.lu@linux.intel.com>
Message-ID: <89dff474-7baa-83ce-d70d-fffc4699d3ce@linux.intel.com>
Date:   Sun, 9 Sep 2018 10:01:17 +0800
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Hi,

The fix has been posted here.

https://lkml.org/lkml/2018/9/8/14

Best regards,
Lu Baolu

On 09/08/2018 09:57 PM, Dmitrii Tcvetkov wrote:
> I've sent the email[1] before to iommu and lkml mailing lists only, but
> according to iommu mailing list archive it wasn't received[2]. I'm
> resending it to Lu Baolu and Joerg Roedel with proper kernel .config
> file. Sorry if the duplication is unnecessary.
> 
> Since 4.19-rc1 my laptop boots with vertical static set of rows of dots
> on the screen instead of proper video output. SSH'ing into it allowed
> to get dmesg-without-pt.log output, PCI device 00:02.0 is VGA
> compatible controller: Intel Corporation HD Graphics 620 (rev 02)
> 
> Appending "iommu=pt" to kernel cmdline allowed to boot with functional
> graphics, but gave dmesg-with-pt.log output.
> 
> Bisect between v4.18 and v4.19-rc1 tags led me to commit
> a7fc93fed94b173e2 (iommu/vt-d: Allocate and free pasid table).
> 
> Reverting this commit allows to build kernel on current master
> (a12ed06ba2d3fa60e), which boots with functional graphical output
> without specifying "iommu=pt".
> Dmesg output is in dmesg-with-revert.log.
> 
> Without the revert current master boots like 4.19-rc1.
> 
> [1] https://lkml.org/lkml/2018/9/7/1081
> [2] https://lists.linuxfoundation.org/pipermail/iommu/2018-September/date.html
>