Revision 31a55cf145f2e3d74a7488e86bd0b33b64250fce authored by Dave Airlie on 19 March 2015, 04:01:42 UTC, committed by Dave Airlie on 19 March 2015, 04:01:42 UTC
   Some urgent regression fixes to booting failures Exynos DRM occured.

   Summary:
   - Fix two urgent null pointer dereference bugs in case of enabling
     or disabling IOMMU. There was two cases to these issues.
     One is that plane->crtc is accessed by exynos_disable_plane()
     when device tree binding is broken so device driver tries
     to release, which means that the mode set operation isn't invoked yet
     so plane->crtc is still NULL and exynos_disable_plane() will access
     NULL pointer. This issue is fixed by checking if the plane->crtc
     is NULL or not in exynos_disable_plane()

     Other is that fimd_wait_for_vblank() is called to avoid from page fault
     with IOMMU before the ctx object is created. At this time,
     fimd_wait_for_vblank() tries to access ctx->crtc but the ctx->crtc
     is still NULL because exynos_drm_crtc_create() isn't called yet.
     This issue is fixed by creating a crtc object and setting it to
     ctx->crtc prior to fimd_wait_for_vblank() call.

     For more details, you can refer to below an e-mail thread,
     http://www.spinics.net/lists/linux-samsung-soc/msg42436.html

   - Remove unnecessary file not used and fix trivial issues.

* 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos:
  drm/exynos: fix the initialization order in FIMD
  drm/exynos: fix typo config name correctly.
  drm/exynos: Check for NULL dereference of crtc
  drm/exynos: IS_ERR() vs NULL bug
  drm/exynos: remove unused files
2 parent s 59caeae + cdbfca8
Raw File
int_sqrt.c
/*
 * Copyright (C) 2013 Davidlohr Bueso <davidlohr.bueso@hp.com>
 *
 *  Based on the shift-and-subtract algorithm for computing integer
 *  square root from Guy L. Steele.
 */

#include <linux/kernel.h>
#include <linux/export.h>

/**
 * int_sqrt - rough approximation to sqrt
 * @x: integer of which to calculate the sqrt
 *
 * A very rough approximation to the sqrt() function.
 */
unsigned long int_sqrt(unsigned long x)
{
	unsigned long b, m, y = 0;

	if (x <= 1)
		return x;

	m = 1UL << (BITS_PER_LONG - 2);
	while (m != 0) {
		b = y + m;
		y >>= 1;

		if (x >= b) {
			x -= b;
			y += m;
		}
		m >>= 2;
	}

	return y;
}
EXPORT_SYMBOL(int_sqrt);
back to top