drm/i915: Polish skl_is_16gb_dimm()

Pass the dimm struct to skl_is_16gb_dimm() rather than passing each
value separately. And let's replace the hardcoded set of values with
some simple arithmetic.

Also fix the byte vs. bit inconsistency in the debug message,
and polish the wording otherwise as well.

v2: Deobfuscate the math (Chris)

Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190306203551.24592-4-ville.syrjala@linux.intel.com

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 45d70ecd90375bdd67cd6c8289e49abbeaf659e5..e35a75be3a2a6d8cc1d8606b4db3b643032ba29d 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1068,6 +1068,11 @@ static void intel_sanitize_options(struct drm_i915_private *dev_priv)
        intel_gvt_sanitize_options(dev_priv);
 }
 
+static int intel_dimm_num_devices(const struct dram_dimm_info *dimm)
+{
+       return dimm->ranks * 64 / (dimm->width ?: 1);
+}
+
 /* Returns total GB for the whole DIMM */
 static int skl_get_dimm_size(u16 val)
 {
@@ -1102,18 +1107,10 @@ static int skl_get_dimm_ranks(u16 val)
 }
 
 static bool
-skl_is_16gb_dimm(u8 ranks, u8 size, u8 width)
+skl_is_16gb_dimm(const struct dram_dimm_info *dimm)
 {
-       if (ranks == 1 && width == 8 && size == 16)
-               return true;
-       else if (ranks == 2 && width == 8 && size == 32)
-               return true;
-       else if (ranks == 1 && width == 16 && size == 8)
-               return true;
-       else if (ranks == 2 && width == 16 && size == 16)
-               return true;
-
-       return false;
+       /* Convert total GB to Gb per DRAM device */
+       return 8 * dimm->size / (intel_dimm_num_devices(dimm) ?: 1) == 16;
 }
 
 static int
@@ -1143,10 +1140,9 @@ skl_dram_get_channel_info(struct dram_channel_info *ch, u32 val)
        else
                ch->ranks = 1;
 
-       ch->is_16gb_dimm = skl_is_16gb_dimm(ch->l_info.ranks, ch->l_info.size,
-                                           ch->l_info.width) ||
-                          skl_is_16gb_dimm(ch->s_info.ranks, ch->s_info.size,
-                                           ch->s_info.width);
+       ch->is_16gb_dimm =
+               skl_is_16gb_dimm(&ch->l_info) ||
+               skl_is_16gb_dimm(&ch->s_info);
 
        DRM_DEBUG_KMS("(size:width:ranks) L(%uGB:X%u:%u) S(%uGB:X%u:%u)\n",
                      ch->l_info.size, ch->l_info.width, ch->l_info.ranks,
@@ -1364,7 +1360,7 @@ intel_get_dram_info(struct drm_i915_private *dev_priv)
                sprintf(bandwidth_str, "unknown");
        DRM_DEBUG_KMS("DRAM bandwidth:%s, total-channels: %u\n",
                      bandwidth_str, dram_info->num_channels);
-       DRM_DEBUG_KMS("DRAM ranks: %u, 16GB-dimm:%s\n",
+       DRM_DEBUG_KMS("DRAM ranks: %u, 16Gb DIMMs: %s\n",
                      dram_info->ranks, yesno(dram_info->is_16gb_dimm));
 }
 

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6f8e9910bb47f2fb2ac8878ad6feceebc49e35ab..84e3e3a0bd1e95663c8a6f682955f13e7e3f7610 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2052,10 +2052,12 @@ struct drm_i915_private {
         */
 };
 
+struct dram_dimm_info {
+       u8 size, width, ranks;
+};
+
 struct dram_channel_info {
-       struct info {
-               u8 size, width, ranks;
-       } l_info, s_info;
+       struct dram_dimm_info l_info, s_info;
        u8 ranks;
        bool is_16gb_dimm;
 };