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<div class="moz-cite-prefix">Yusef is using an ARM platform. As far
as I know he already tried to shuffle the static allocation for
the MMIO address spaces around without much luck.<br>
<br>
The only option I see would be to use the PCIe bridge trick I've
mentioned below, but this is really so hacky that I won't
recommend that.<br>
<br>
Christian.<br>
<br>
Am 18.02.20 um 15:43 schrieb Bridgman, John:<br>
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[AMD Official Use Only - Internal Distribution Only]<br>
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>And we already checked, 256MB is unfortunately the minimum
you can resize the VRAM BAR on the E9171 to.<br>
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Ahh, OK... I didn't realize we had already looked into that. I
guess that approach isn't going to work.
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Yusef, guessing you are using a 32-bit CPU ? Is it possible to
talk to whoever does SBIOS for your platform to see if you
could maybe reduce address space allocated to RAM and bump up
the MMIO space ?<br>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b>
Christian König <a class="moz-txt-link-rfc2396E" href="mailto:ckoenig.leichtzumerken@gmail.com"><ckoenig.leichtzumerken@gmail.com></a><br>
<b>Sent:</b> February 18, 2020 9:19 AM<br>
<b>To:</b> Bridgman, John <a class="moz-txt-link-rfc2396E" href="mailto:John.Bridgman@amd.com"><John.Bridgman@amd.com></a>;
Alex Deucher <a class="moz-txt-link-rfc2396E" href="mailto:alexdeucher@gmail.com"><alexdeucher@gmail.com></a>; Yusuf
Altıparmak <a class="moz-txt-link-rfc2396E" href="mailto:yusufalti1997@gmail.com"><yusufalti1997@gmail.com></a><br>
<b>Cc:</b> amd-gfx list
<a class="moz-txt-link-rfc2396E" href="mailto:amd-gfx@lists.freedesktop.org"><amd-gfx@lists.freedesktop.org></a><br>
<b>Subject:</b> Re: writing custom driver for VGA
emulation ?</font>
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<div class="x_moz-cite-prefix">The problem Yusuf runs into
is that his platform has multiple PCIe root hubs, but only
512MB of MMIO address space. That is not enough to fit all
the BARs of an E9171 into.<br>
<br>
But without the BARs neither the VGA emulation nor amdgpu
not anything else will work correctly.<br>
<br>
And we already checked, 256MB is unfortunately the minimum
you can resize the VRAM BAR on the E9171 to.<br>
<br>
What could maybe work is to trick the upstream bridge of
the VGA device into not routing all the addresses to the
BARs and actually use only a smaller portion of visible
VRAM. But that would be highly experimental and requires a
rather big hack into the PCI(e) subsystem in the Linux
kernel.<br>
<br>
Regards,<br>
Christian.<br>
<br>
Am 18.02.20 um 15:08 schrieb Bridgman, John:<br>
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[AMD Official Use Only - Internal Distribution Only]<br>
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<div>Does the VBIOS come up with something like a splash
screen, ie is VBIOS able to initialize and drive the
card ?<br>
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<div><br>
</div>
<div>If so then another option might be to use a VESA
driver rather than VGA. <br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> amd-gfx
<a class="x_moz-txt-link-rfc2396E" href="mailto:amd-gfx-bounces@lists.freedesktop.org" moz-do-not-send="true">
<amd-gfx-bounces@lists.freedesktop.org></a>
on behalf of Alex Deucher <a class="x_moz-txt-link-rfc2396E" href="mailto:alexdeucher@gmail.com" moz-do-not-send="true">
<alexdeucher@gmail.com></a><br>
<b>Sent:</b> February 18, 2020 8:50 AM<br>
<b>To:</b> Yusuf Altıparmak <a class="x_moz-txt-link-rfc2396E" href="mailto:yusufalti1997@gmail.com" moz-do-not-send="true">
<yusufalti1997@gmail.com></a><br>
<b>Cc:</b> amd-gfx list <a class="x_moz-txt-link-rfc2396E" href="mailto:amd-gfx@lists.freedesktop.org" moz-do-not-send="true">
<amd-gfx@lists.freedesktop.org></a><br>
<b>Subject:</b> Re: writing custom driver for VGA
emulation ?</font>
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<div class="x_PlainText">On Tue, Feb 18, 2020 at
2:56 AM Yusuf Altıparmak<br>
<a class="x_moz-txt-link-rfc2396E" href="mailto:yusufalti1997@gmail.com" moz-do-not-send="true"><yusufalti1997@gmail.com></a>
wrote:<br>
><br>
> Hello AMD team;<br>
><br>
> I have E 9171 GPU and want to use it on a
embedded system which has limited MMIO space
on PCIe bus (MAX 512 MB).<br>
><br>
> I received feedbacks that I can only use
VGA emulation with this memory space. I was
unable to get 'amdgpu' driver working with
Xorg due to I had many errors(firmwares are
not loading) in each step and tired of solving
them one by one.<br>
><br>
> I want to write a simple custom driver
for this GPU with kernel version 4.19.<br>
> Is it possible to print some colors on
screen with a custom driver over PCIe
communication ? or writing some words on
screen as VGA ?<br>
><br>
> If answer is yes, then which code pieces
(on amdgpu driver folder) or reference
documentation should I use? I have Register
Reference Guide.pdf.<br>
><br>
> I will be appreciated for your guidance.<br>
<br>
That is not going to do what you want on your
platform. The VGA<br>
emulation requires that you set up the card
first to enable it, which<br>
in turn requires MMIO access and thus you are
back to square one.<br>
<br>
Alex<br>
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