Thread (269 messages) 269 messages, 18 authors, 2014-11-11

[linux-sunxi] Re: [PATCH 4/4] simplefb: add clock handling code

From: jonsmirl at gmail.com <hidden>
Date: 2014-08-27 12:56:44
Also in: linux-fbdev

On Wed, Aug 27, 2014 at 8:50 AM, Hans de Goede [off-list ref] wrote:
Hi,

On 08/27/2014 02:44 PM, jonsmirl at gmail.com wrote:

<snip>
quoted
quoted
1) Serving as *the* fb until a kms driver is present
Why can't we whip together a real device specific fbdev driver and
quit trying to run without a device specific driver in place? History
has shown that to be bad idea except during early boot when there
isn't a choice.
Writing a kms driver and getting it upstream is not a simple task, and
starting with a too limited implementation is dangerous as we need to get
the devicetree binding first from the get go.
I didn't say write a kms driver, I said write a fbdev driver.  Look in
drivers/video/fbdev. fbdev drivers are used on many embedded systems.
Its what we used for years before kms came along.
IOW this is not really a realistic answer to problem 1.

<snip>
quoted
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2) Allowing for output of early kernel boot messages.
For this to work the kernel needs to know two things - address of the
framebuffer and the x/y layout. Then just nuke this display when the
kernel finishes the boot process.
Please read my earlier mails on how completely flawed it is to write
"when the kernel finishes the boot process". The problem is that there
is no way to really determine when this happens.
Let me rephrase that, when the existing code in the clk system and
regulator systems decide to do their clean up the display will get
nuked.

Regards,

Hans

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-- 
Jon Smirl
jonsmirl at gmail.com
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