drm/i915: Fix buffer overflow in dsi_calc_mnp()
smatch complain:
drivers/gpu/drm/i915/intel_dsi_pll.c:101 dsi_calc_mnp() error: buffer
overflow 'lfsr_converts' 39 <= 4294967234
and looks justified in doing so.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1467470166-31717-7-git-send-email-chris@chris-wilson.co.uk
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
diff --git a/drivers/gpu/drm/i915/intel_dsi_pll.c b/drivers/gpu/drm/i915/intel_dsi_pll.c
index 4f9930b..1fcddeb 100644
--- a/drivers/gpu/drm/i915/intel_dsi_pll.c
+++ b/drivers/gpu/drm/i915/intel_dsi_pll.c
@@ -55,12 +55,10 @@
struct intel_crtc_state *config,
int target_dsi_clk)
{
- unsigned int calc_m = 0, calc_p = 0;
unsigned int m_min, m_max, p_min = 2, p_max = 6;
unsigned int m, n, p;
- int ref_clk;
- int delta = target_dsi_clk;
- u32 m_seed;
+ unsigned int calc_m, calc_p;
+ int delta, ref_clk;
/* target_dsi_clk is expected in kHz */
if (target_dsi_clk < 300000 || target_dsi_clk > 1150000) {
@@ -80,6 +78,10 @@
m_max = 92;
}
+ calc_p = p_min;
+ calc_m = m_min;
+ delta = abs(target_dsi_clk - (m_min * ref_clk) / (p_min * n));
+
for (m = m_min; m <= m_max && delta; m++) {
for (p = p_min; p <= p_max && delta; p++) {
/*
@@ -97,11 +99,10 @@
}
/* register has log2(N1), this works fine for powers of two */
- n = ffs(n) - 1;
- m_seed = lfsr_converts[calc_m - 62];
config->dsi_pll.ctrl = 1 << (DSI_PLL_P1_POST_DIV_SHIFT + calc_p - 2);
- config->dsi_pll.div = n << DSI_PLL_N1_DIV_SHIFT |
- m_seed << DSI_PLL_M1_DIV_SHIFT;
+ config->dsi_pll.div =
+ (ffs(n) - 1) << DSI_PLL_N1_DIV_SHIFT |
+ (u32)lfsr_converts[calc_m - 62] << DSI_PLL_M1_DIV_SHIFT;
return 0;
}