Re: [PATCH v5 4/7] video: add generic framebuffer eviction

[David Herrmann <dh.herrmann@gmail.com>]

Hi

On Sat, Sep 3, 2016 at 2:06 PM, Noralf Trønnes <noralf@tronnes.org> wrote:
>
> Den 02.09.2016 10:22, skrev David Herrmann:
>>
>> There are several situations where we want hardware handover from an early
>> boot GFX driver (e.g., vgacon, vesafb, efifb, simplefb) to a full fletched
>> GFX driver (e.g., most DRM drivers). So far, we relied on
>> remove_conflicting_framebuffers() to do this for us, however, this had a
>> bunch of downsides:
>>
>>    o It only removes conflicting fbdev drivers. It does not drop vgacon,
>>      early boot console drivers, conflicting DRM drivers, etc.
>>
>>    o It only unloads the fbdev driver, it does not modify the underlying
>>      device or resources. In case of "screen_info" drivers (e.g., efifb)
>>      this is fine, since no resources are pinned. However, if the driver
>>      binds to a platform-device like "simple-framebuffer", we must make
>>      sure to unregister that device as well. Otherwise, pinned resources
>>      like IORESOURCE_MEM stay around, triggering WARN_ONs if the following
>>      driver requests those resources.
>>
>>    o It is only available if CONFIG_FB is selected.
>>
>> This commit adds a new infrastructure that manages system-framebuffers
>> (short: sysfb). The initial commit provides conflict-resolution for
>> system-framebuffers. At its core it provides sysfb_evict_conflicts(),
>> which implements conflict detection and removal for all known types of
>> GFX driver hand-overs. So far, this includes platform-device removal,
>> fbdev-firmware-device removal, vgacon removal and VBE detection. To
>> further simplify the callers, it also provides helpers to figure out what
>> hand-over to do, based on the device the new drivers binds to:
>>
>>    o PCI drivers can use sysfb_evict_conflicts_pci(), which will figure
>> out
>>      the apertures automatically, and does VGA/VBE detection.
>>
>>    o Generic firmware drivers that might be shadowed at any address in
>>      memory can use sysfb_evict_conflicts_firmware(), basically removing
>>      *all* firmware framebuffers in effect.
>>
>> This only adds the generic sysfb helpers. No users are converted, yet.
>>
>> Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
>> ---
>>   drivers/video/Kconfig  |   4 +
>>   drivers/video/Makefile |   1 +
>>   drivers/video/sysfb.c  | 327
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>   include/linux/sysfb.h  |  34 +++++
>>   4 files changed, 366 insertions(+)
>>   create mode 100644 drivers/video/sysfb.c
>>   create mode 100644 include/linux/sysfb.h
>>
>> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
>> index 3c20af9..56a8294 100644
>> --- a/drivers/video/Kconfig
>> +++ b/drivers/video/Kconfig
>> @@ -36,6 +36,10 @@ config VIDEOMODE_HELPERS
>>   config HDMI
>>         bool
>>   +config SYSFB
>> +       bool
>> +       select DUMMY_CONSOLE if VT
>> +
>>   if VT
>>         source "drivers/video/console/Kconfig"
>>   endif
>> diff --git a/drivers/video/Makefile b/drivers/video/Makefile
>> index 9ad3c17..df7bd75 100644
>> --- a/drivers/video/Makefile
>> +++ b/drivers/video/Makefile
>> @@ -1,5 +1,6 @@
>>   obj-$(CONFIG_VGASTATE)            += vgastate.o
>>   obj-$(CONFIG_HDMI)                += hdmi.o
>> +obj-$(CONFIG_SYSFB)              += sysfb.o
>>     obj-$(CONFIG_VT)              += console/
>>   obj-$(CONFIG_LOGO)              += logo/
>> diff --git a/drivers/video/sysfb.c b/drivers/video/sysfb.c
>> new file mode 100644
>> index 0000000..00585c9
>> --- /dev/null
>> +++ b/drivers/video/sysfb.c
>> @@ -0,0 +1,327 @@
>> +/*
>> + * Copyright (C) 2013-2016 Red Hat, Inc.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> it
>> + * under the terms of the GNU Lesser General Public License as published
>> by the
>> + * Free Software Foundation; either version 2.1 of the License, or (at
>> your
>> + * option) any later version.
>> + */
>> +
>> +#define pr_fmt(fmt) "sysfb: " fmt
>> +#include <linux/console.h>
>> +#include <linux/device.h>
>> +#include <linux/err.h>
>> +#include <linux/export.h>
>> +#include <linux/fb.h>
>> +#include <linux/ioport.h>
>> +#include <linux/kernel.h>
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/pci.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/slab.h>
>> +#include <linux/sysfb.h>
>> +#include <linux/vt.h>
>> +
>> +static bool sysfb_evict_match_resource(struct sysfb_evict_ctx *ctx,
>> +                                      struct resource *mem)
>> +{
>> +       struct aperture *g;
>> +       unsigned int i;
>> +
>> +       for (i = 0; i < ctx->ap->count; ++i) {
>> +               g = &ctx->ap->ranges[i];
>> +
>> +               if (mem->start == g->base)
>> +                       return true;
>> +               if (mem->start >= g->base && mem->end < g->base + g->size)
>> +                       return true;
>> +               if ((ctx->flags & SYSFB_EVICT_VBE) && mem->start ==
>> 0xA0000)
>> +                       return true;
>> +       }
>> +
>> +       return false;
>> +}
>> +
>> +static int sysfb_evict_platform_device(struct device *dev, void
>> *userdata)
>> +{
>> +       struct sysfb_evict_ctx *ctx = userdata;
>> +       struct platform_device *pdev = to_platform_device(dev);
>> +       struct resource *mem;
>> +
>> +       if (!pdev->name)
>> +               return 0;
>> +
>> +       if (!strcmp(pdev->name, "simple-framebuffer")) {
>
>
> This doesn't work in my case where the device comes from DT and the name
> also contains the address: pdev->name=1e887000.framebuffer
>
> This is one way of solving it:
>
>        if (!pdev->dev.driver || !pdev->dev.driver->name)
>                 return 0;
>
>        if (!strcmp(pdev->dev.driver->name, "simple-framebuffer")) {

Thanks for the hint, but this would skip devices that are not bound.
How about the attached hunk?

Thanks
David

diff --git a/drivers/video/sysfb.c b/drivers/video/sysfb.c
index 0f039c6..a4ace3f 100644
--- a/drivers/video/sysfb.c
+++ b/drivers/video/sysfb.c
@@ -50,10 +50,8 @@ static int sysfb_evict_platform_device
        struct platform_device *pdev = to_platform_device(dev);
        struct resource *mem;

-       if (!pdev->name)
-               return 0;
-
-       if (!strcmp(pdev->name, "simple-framebuffer")) {
+       if ((pdev->name && !strcmp(pdev->name, "simple-framebuffer")) ||
+           of_device_is_compatible(pdev->dev.of_node, "simple-framebuffer")) {
                mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
                if (!mem)
                        return 0;
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