2017-11-22 20:56:55

by Kees Cook

[permalink] [raw]
Subject: i915: enum intel_dpll_id cast

Hi,

While doing Clang test builds, this was reported:

drivers/gpu/drm/i915/intel_ddi.c:1481:30: warning: implicit conversion
from enumeration type 'enum port' to different enumeration type 'enum
intel_dpll_id' [-Wenum-conversion]
enum intel_dpll_id pll_id = port;
~~~~~~ ^~~~

Which is from:

static void bxt_ddi_clock_get(struct intel_encoder *encoder,
struct intel_crtc_state *pipe_config)
{
struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
enum port port = intel_ddi_get_encoder_port(encoder);
enum intel_dpll_id pll_id = port;

pipe_config->port_clock = bxt_calc_pll_link(dev_priv, pll_id);
...
}

In looking at it, it seems to be harmless if as enum port has a
smaller range than enum intel_dpll_id. I just wanted to check if maybe
something might go weird, since DPLL_ID_LCPLL_2700 maybe ends up
getting seen as I915_MAX_PORTS?

enum port {
PORT_NONE = -1,
PORT_A = 0,
PORT_B,
PORT_C,
PORT_D,
PORT_E,
I915_MAX_PORTS
};

enum intel_dpll_id {
...
DPLL_ID_LCPLL_2700 = 5,
...
};


Thanks!

-Kees

--
Kees Cook
Pixel Security

From 1584886338268453018@xxx Thu Nov 23 19:29:55 +0000 2017
X-GM-THRID: 1584886338268453018
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread