At Wed, 18 Dec 2013 12:48:03 +0100,
David Herrmann wrote:
>
> If we probe a real hw driver for graphics devices, we need to unload any
> generic fallback driver like efifb/vesafb/simplefb on the system
> framebuffer. This is currently done via remove_conflicting_framebuffers()
> in fbmem.c. However, this only removes the fbdev driver, not the fake
> platform devices underneath. This hasn't been a problem so far, as efifb
> and vesafb didn't store any resources there. However, with simplefb this
> changed.
>
> To correctly release the IORESOURCE_MEM resources of simple-framebuffer
> platform devices, we need to unregister the underlying platform device
> *before* probing any new hw driver. This patch adds sysfb_unregister() for
> that purpose. It can be called from any context (except from the
> platform-device ->remove callback path) and synchronously unloads any
> global sysfb and prevents new sysfbs from getting registered. Thus, you
> can call it even before any sysfb has been loaded.
>
> This also changes remove_conflicting_framebuffer() to call this helper
> *before* trying it's fbdev heuristic to remove conflicting drivers.
>
> Signed-off-by: David Herrmann <dh.herrmann@xxxxxxxxx>
> ---
> Hi
>
> This is imho the clean version of Takashi's fix. However, it gets pretty huge. I
> wouldn't object to marking CONFIG_X86_SYSFB broken in the stable series and get
> this in for 3.14. Your call..
>
> This patch basically simulates an unplug event for system-framebuffers when
> loading real hardware drivers. To trigger it, call sysfb_unregister(). You can
> optionally pass an aperture-struct and primary-flag similar to
> remove_conflicting_framebuffers(). If they're not passed, we remove it
> unconditionally.
>
> Untested, but my kernel compiles are already running. If my tests succeed and
> nobody has objections, I can resend it as proper PATCH and marked for stable.
> And maybe split the fbmem and sysfb changes into two patches..
>
> Thanks
> David
>
> arch/x86/include/asm/sysfb.h | 10 ++++
> arch/x86/kernel/sysfb.c | 103 +++++++++++++++++++++++++++++++++++++--
> arch/x86/kernel/sysfb_simplefb.c | 5 +-
> drivers/video/fbmem.c | 16 ++++++
> 4 files changed, 128 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/sysfb.h b/arch/x86/include/asm/sysfb.h
> index 2aeb3e2..713bc17 100644
> --- a/arch/x86/include/asm/sysfb.h
> +++ b/arch/x86/include/asm/sysfb.h
> @@ -11,6 +11,7 @@
> * any later version.
> */
>
> +#include <linux/fb.h>
> #include <linux/kernel.h>
> #include <linux/platform_data/simplefb.h>
> #include <linux/screen_info.h>
> @@ -59,6 +60,15 @@ struct efifb_dmi_info {
> int flags;
> };
>
> +__init struct platform_device *sysfb_alloc(const char *name,
> + int id,
> + const struct resource *res,
> + unsigned int res_num,
> + const void *data,
> + size_t data_size);
> +__init int sysfb_register(struct platform_device *dev);
> +void sysfb_unregister(const struct apertures_struct *apert, bool primary);
> +
> #ifdef CONFIG_EFI
>
> extern struct efifb_dmi_info efifb_dmi_list[];
> diff --git a/arch/x86/kernel/sysfb.c b/arch/x86/kernel/sysfb.c
> index 193ec2c..3d4554e 100644
> --- a/arch/x86/kernel/sysfb.c
> +++ b/arch/x86/kernel/sysfb.c
> @@ -33,11 +33,106 @@
> #include <linux/init.h>
> #include <linux/kernel.h>
> #include <linux/mm.h>
> +#include <linux/mutex.h>
> #include <linux/platform_data/simplefb.h>
> #include <linux/platform_device.h>
> #include <linux/screen_info.h>
> #include <asm/sysfb.h>
>
> +static DEFINE_MUTEX(sysfb_lock);
> +static struct platform_device *sysfb_dev;
> +
> +/* register @dev as sysfb; takes ownership over @dev */
> +__init int sysfb_register(struct platform_device *dev)
> +{
> + int r = 0;
> +
> + mutex_lock(&sysfb_lock);
> + if (!sysfb_dev) {
> + r = platform_device_add(dev);
> + if (r < 0)
> + put_device(&dev->dev);
> + else
> + sysfb_dev = dev;
> + } else {
> + /* if there already is/was a sysfb, destroy @pd but return 0 */
> + platform_device_put(dev);
> + }
> + mutex_unlock(&sysfb_lock);
> +
> + return r;
> +}
Since sysfb_alloc() always follows sysfb_register() and they are
always coupled, we can simply combine both to one?
Also, do we really need a mutex? The functions in fbmem.c are already
in registeration_lock, so if this is called only from there, it should
be fine without an extra lock here. So, the function can be
simplified like:
int sysfb_register(const char *name, int id, const struct resource *res,
unsigned int res_num, const void *data, size_t data_size)
{
struct platform_device *pdev;
if (sysfb_dev)
return ret;
pdev = platform_device_register_resndata(....);
if (IS_ERR(pdev))
return PTR_ERR(pdev);
sysfb_dev = pdev;
return 0;
}
> +
> +static bool sysfb_match(const struct apertures_struct *apert, bool primary)
> +{
> + struct screen_info *si = &screen_info;
> + unsigned int i;
> + const struct aperture *a;
> +
> + if (!apert || primary)
> + return true;
> +
> + for (i = 0; i < apert->count; ++i) {
> + a = &apert->ranges[i];
> + if (a->base >= si->lfb_base &&
> + a->base < si->lfb_base + ((u64)si->lfb_size << 16))
> + return true;
> + if (si->lfb_base >= a->base &&
> + si->lfb_base < a->base + a->size)
> + return true;
> + }
> +
> + return false;
> +}
> +
> +/* unregister the sysfb and prevent new sysfbs from getting registered */
> +void sysfb_unregister(const struct apertures_struct *apert, bool primary)
> +{
> +
> + mutex_lock(&sysfb_lock);
> + if (!IS_ERR(sysfb_dev)) {
> + if (sysfb_dev) {
> + if (sysfb_match(apert, primary)) {
> + platform_device_del(sysfb_dev);
> + platform_device_put(sysfb_dev);
> + sysfb_dev = ERR_PTR(-EALREADY);
> + }
> + } else {
> + sysfb_dev = ERR_PTR(-EALREADY);
> + }
> + }
> + mutex_unlock(&sysfb_lock);
> +}
Simpler would be like:
void sysfb_unregister(const struct apertures_struct *apert, bool primary)
{
if (sysfb_dev && sysfb_match(apert, primary)) {
platform_device_unregister(sysfb_dev);
sysfb_dev = NULL;
}
}
> +
> +__init struct platform_device *sysfb_alloc(const char *name,
> + int id,
> + const struct resource *res,
> + unsigned int res_num,
> + const void *data,
> + size_t data_size)
> +{
> + struct platform_device *pd;
> + int ret;
> +
> + pd = platform_device_alloc(name, id);
> + if (!pd)
> + return ERR_PTR(-ENOMEM);
> +
> + ret = platform_device_add_resources(pd, res, res_num);
> + if (ret)
> + goto err;
> +
> + ret = platform_device_add_data(pd, data, data_size);
> + if (ret)
> + goto err;
> +
> + return pd;
I don't think we need to open-code this if we can use
platform_device_register_*() helper.
> +
> +err:
> + platform_device_put(pd);
> + return ERR_PTR(ret);
> +}
> +
> static __init int sysfb_init(void)
> {
> struct screen_info *si = &screen_info;
> @@ -65,9 +160,11 @@ static __init int sysfb_init(void)
> else
> name = "platform-framebuffer";
>
> - pd = platform_device_register_resndata(NULL, name, 0,
> - NULL, 0, si, sizeof(*si));
> - return IS_ERR(pd) ? PTR_ERR(pd) : 0;
> + pd = sysfb_alloc(name, 0, NULL, 0, si, sizeof(*si));
> + if (IS_ERR(pd))
> + return PTR_ERR(pd);
> +
> + return sysfb_register(pd);
> }
>
> /* must execute after PCI subsystem for EFI quirks */
> diff --git a/arch/x86/kernel/sysfb_simplefb.c b/arch/x86/kernel/sysfb_simplefb.c
> index 86179d4..8e7bd23 100644
> --- a/arch/x86/kernel/sysfb_simplefb.c
> +++ b/arch/x86/kernel/sysfb_simplefb.c
> @@ -86,10 +86,9 @@ __init int create_simplefb(const struct screen_info *si,
> if (res.end <= res.start)
> return -EINVAL;
>
> - pd = platform_device_register_resndata(NULL, "simple-framebuffer", 0,
> - &res, 1, mode, sizeof(*mode));
> + pd = sysfb_alloc("simple-framebuffer", 0, &res, 1, mode, sizeof(*mode));
> if (IS_ERR(pd))
> return PTR_ERR(pd);
>
> - return 0;
> + return sysfb_register(pd);
> }
> diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
> index 010d191..53e3894 100644
> --- a/drivers/video/fbmem.c
> +++ b/drivers/video/fbmem.c
> @@ -35,6 +35,9 @@
>
> #include <asm/fb.h>
>
> +#if IS_ENABLED(CONFIG_X86_SYSFB)
> +#include <asm/sysfb.h>
> +#endif
>
> /*
> * Frame buffer device initialization and setup routines
> @@ -1604,6 +1607,14 @@ static void do_remove_conflicting_framebuffers(struct apertures_struct *a,
> }
> }
>
> +static void remove_conflicting_sysfb(const struct apertures_struct *apert,
> + bool primary)
> +{
> +#if IS_ENABLED(CONFIG_X86_SYSFB)
> + sysfb_unregister(apert, primary);
> +#endif
I noticed that sysfb.c is built even without CONFIG_X86_SYSFB.
So this can be called even for non-sysfb case (which is also good to
release the unused platform_device).
That is, this (and the above) can be #ifdef CONFIG_X86 instead.
thanks,
Takashi
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