Date:   Fri, 31 Mar 2023 11:00:43 +0200
From:   Petr Tesařík <petr@...arici.cz>
To:     Juerg Haefliger <juergh@...ton.me>
Cc:     Petr Tesarik <petrtesarik@...weicloud.com>,
        Christoph Hellwig <hch@....de>,
        Jonathan Corbet <corbet@....net>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        Borislav Petkov <bp@...e.de>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Damien Le Moal <damien.lemoal@...nsource.wdc.com>,
        Kim Phillips <kim.phillips@....com>,
        "Steven Rostedt (Google)" <rostedt@...dmis.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:DMA MAPPING HELPERS" <iommu@...ts.linux.dev>,
        Roberto Sassu <roberto.sassu@...wei.com>,
        Alexander Graf <graf@...zon.com>
Subject: Re: [RFC v1 3/4] swiotlb: Allow dynamic allocation of bounce
 buffers

Hi Juerg,

On Fri, 31 Mar 2023 07:26:09 +0000
Juerg Haefliger <juergh@...ton.me> wrote:

> On Tue, 28 Mar 2023 09:54:35 +0200
> Petr Tesarik <petrtesarik@...weicloud.com> wrote:
> 
>[...]
> > Anyway, I suspected that the buffers need not be imported into the vc4
> > driver (also hinted by Eric Anholt in a 2018 blog post [1]), and it
> > seems I was right. I encountered the issue with Ubuntu 22.10; I
> > installed latest openSUSE Tumbleweed yesterday, and I was not able to
> > reproduce the issue there, most likely because the Mesa drivers have
> > been fixed meanwhile. This makes the specific case of the Raspberry Pi 4
> > drivers moot. The issue may still affect other combinations of drivers,
> > but I don't have any other real-world example ATM.  
> 
> I'm only seeing this problem with Wayland, no issue when switching Ubuntu to
> X. It seems Tumbleweed is using X by default.

I know; I was the team lead of SUSE low-level graphics engineers until
end of last year... I have just double-checked, but this output of
wayland-info in the GNOME session accessed over RDP is quite convincing:

interface: 'wl_compositor',                              version:  5, name:  1
interface: 'wl_shm',                                     version:  1, name:  2
        formats (fourcc):
        0x48344258 = 'XB4H'
        0x48344241 = 'AB4H'
        0x48345258 = 'XR4H'
        0x48345241 = 'AR4H'
        0x30334258 = 'XB30'
        0x30334241 = 'AB30'
        0x30335258 = 'XR30'
        0x30335241 = 'AR30'
        0x36314752 = 'RG16'
        0x34324258 = 'XB24'
        0x34324241 = 'AB24'
                 1 = 'XR24'
                 0 = 'AR24'
interface: 'wl_output',                                  version:  3, name:  3
        x: 0, y: 0, scale: 1,
        physical_width: 430 mm, physical_height: 270 mm,
        make: 'FUS', model: 'P20W-5 ECO',
        subpixel_orientation: unknown, output_transform: normal,
        mode:
                width: 1680 px, height: 1050 px, refresh: 59.954 Hz,
                flags: current preferred
interface: 'zxdg_output_manager_v1',                     version:  3, name:  4
        xdg_output_v1
                output: 3
                name: 'HDMI-1'
                description: 'Fujitsu Siemens Computers GmbH 20"'
                logical_x: 0, logical_y: 0
                logical_width: 1680, logical_height: 1050
interface: 'wl_data_device_manager',                     version:  3, name:  5
interface: 'zwp_primary_selection_device_manager_v1',    version:  1, name:  6
interface: 'wl_subcompositor',                           version:  1, name:  7
interface: 'xdg_wm_base',                                version:  4, name:  8
interface: 'gtk_shell1',                                 version:  5, name:  9
interface: 'wp_viewporter',                              version:  1, name: 10
interface: 'zwp_pointer_gestures_v1',                    version:  3, name: 11
interface: 'zwp_tablet_manager_v2',                      version:  1, name: 12
interface: 'wl_seat',                                    version:  8, name: 13
        name: seat0
        capabilities: pointer keyboard
        keyboard repeat rate: 33
        keyboard repeat delay: 500
interface: 'zwp_relative_pointer_manager_v1',            version:  1, name: 14
interface: 'zwp_pointer_constraints_v1',                 version:  1, name: 15
interface: 'zxdg_exporter_v1',                           version:  1, name: 16
interface: 'zxdg_importer_v1',                           version:  1, name: 17
interface: 'zwp_linux_dmabuf_v1',                        version:  3, name: 18
        formats (fourcc) and modifiers (names):
        0x48344258 = 'XB4H'; 0x00ffffffffffffff = INVALID
        0x48344241 = 'AB4H'; 0x00ffffffffffffff = INVALID
        0x36314752 = 'RG16'; 0x00ffffffffffffff = INVALID
        0x30334258 = 'XB30'; 0x00ffffffffffffff = INVALID
        0x30335258 = 'XR30'; 0x00ffffffffffffff = INVALID
        0x30334241 = 'AB30'; 0x00ffffffffffffff = INVALID
        0x30335241 = 'AR30'; 0x00ffffffffffffff = INVALID
        0x34324258 = 'XB24'; 0x00ffffffffffffff = INVALID
        0x34325258 = 'XR24'; 0x00ffffffffffffff = INVALID
        0x34324241 = 'AB24'; 0x00ffffffffffffff = INVALID
        0x34325241 = 'AR24'; 0x00ffffffffffffff = INVALID
interface: 'wp_single_pixel_buffer_manager_v1',          version:  1, name: 19
interface: 'zwp_keyboard_shortcuts_inhibit_manager_v1',  version:  1, name: 20
interface: 'zwp_text_input_manager_v3',                  version:  1, name: 21
interface: 'wp_presentation',                            version:  1, name: 22
        presentation clock id: 1 (CLOCK_MONOTONIC)
interface: 'xdg_activation_v1',                          version:  1, name: 23

Petr T

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