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SubjectRe: [PATCH 8/9] gma500: frame buffer locking
On Fri, Aug 26, 2011 at 10:45:47AM -0700, Greg KH wrote:
> On Fri, Aug 26, 2011 at 11:19:58AM +0100, Alan Cox wrote:
> > From: Alan Cox <alan@linux.intel.com>
> >
> > If we are the console then a printk can hit us with a spin lock held (and
> > in fact the kernel will do its best to take printing lock).
> >
> > In that case we cannot politely sleep when synching after an accelerated op
> > but must behave obnixously to be sure of getting the bits out.
> >
> > Signed-off-by: Alan Cox <alan@linux.intel.com>
> > ---
> >
> > drivers/staging/gma500/accel_2d.c | 10 ++++++----
> > drivers/staging/gma500/psb_drv.c | 2 +-
> > drivers/staging/gma500/psb_drv.h | 2 +-
> > kernel/printk.c | 2 +-
> > 4 files changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/staging/gma500/accel_2d.c b/drivers/staging/gma500/accel_2d.c
> > index be92371..114b99a 100644
> > --- a/drivers/staging/gma500/accel_2d.c
> > +++ b/drivers/staging/gma500/accel_2d.c
> > @@ -111,8 +111,9 @@ static int psbfb_2d_submit(struct drm_psb_private *dev_priv, uint32_t *cmdbuf,
> > int ret = 0;
> > int i;
> > unsigned submit_size;
> > + unsigned long flags;
> >
> > - mutex_lock(&dev_priv->mutex_2d);
> > + spin_lock_irqsave(&dev_priv->lock_2d, flags);
> > while (size > 0) {
> > submit_size = (size < 0x60) ? size : 0x60;
> > size -= submit_size;
> > @@ -127,7 +128,7 @@ static int psbfb_2d_submit(struct drm_psb_private *dev_priv, uint32_t *cmdbuf,
> >
> > (void)PSB_RSGX32(PSB_SGX_2D_SLAVE_PORT + i - 4);
> > }
> > - mutex_unlock(&dev_priv->mutex_2d);
> > + spin_unlock_irqrestore(&dev_priv->lock_2d, flags);
> > return ret;
> > }
> >
> > @@ -327,8 +328,9 @@ int psbfb_sync(struct fb_info *info)
> > struct drm_psb_private *dev_priv = dev->dev_private;
> > unsigned long _end = jiffies + DRM_HZ;
> > int busy = 0;
> > + unsigned long flags;
> >
> > - mutex_lock(&dev_priv->mutex_2d);
> > + spin_lock_irqsave(&dev_priv->lock_2d, flags);
> > /*
> > * First idle the 2D engine.
> > */
> > @@ -357,7 +359,7 @@ int psbfb_sync(struct fb_info *info)
> > _PSB_C2B_STATUS_BUSY) != 0);
> >
> > out:
> > - mutex_unlock(&dev_priv->mutex_2d);
> > + spin_unlock_irqrestore(&dev_priv->lock_2d, flags);
> > return (busy) ? -EBUSY : 0;
> > }
> >
> > diff --git a/drivers/staging/gma500/psb_drv.c b/drivers/staging/gma500/psb_drv.c
> > index 34cf24a..9470af9 100644
> > --- a/drivers/staging/gma500/psb_drv.c
> > +++ b/drivers/staging/gma500/psb_drv.c
> > @@ -228,7 +228,7 @@ static int psb_do_init(struct drm_device *dev)
> >
> >
> > spin_lock_init(&dev_priv->irqmask_lock);
> > - mutex_init(&dev_priv->mutex_2d);
> > + spin_lock_init(&dev_priv->lock_2d);
> >
> > PSB_WSGX32(0x00000000, PSB_CR_BIF_BANK0);
> > PSB_WSGX32(0x00000000, PSB_CR_BIF_BANK1);
> > diff --git a/drivers/staging/gma500/psb_drv.h b/drivers/staging/gma500/psb_drv.h
> > index 9cbb494..11d963a 100644
> > --- a/drivers/staging/gma500/psb_drv.h
> > +++ b/drivers/staging/gma500/psb_drv.h
> > @@ -612,7 +612,7 @@ struct drm_psb_private {
> > void (*exit_idle)(struct drm_device *dev, u32 update_src);
> >
> > /* 2D acceleration */
> > - struct mutex mutex_2d;
> > + spinlock_t lock_2d;
> >
> > /* FIXME: Arrays anyone ? */
> > struct mdfld_dsi_encoder *encoder0;
> > diff --git a/kernel/printk.c b/kernel/printk.c
> > index e861488..af2eec8 100644
> > --- a/kernel/printk.c
> > +++ b/kernel/printk.c
> > @@ -512,7 +512,7 @@ static void __call_console_drivers(unsigned start, unsigned end)
> > struct console *con;
> >
> > for_each_console(con) {
> > - if (exclusive_console && con != exclusive_console)
> > + if (0 && exclusive_console && con != exclusive_console)
> > continue;
> > if ((con->flags & CON_ENABLED) && con->write &&
> > (cpu_online(smp_processor_id()) ||
>
> Are you sure you want this in the tree? I don't feel comfortable making
> this fix just for one staging driver right now, do you?

I've applied the other 8 patches here, skipping this one.

greg k-h


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