drm/i915/display: Store compressed bpp in U6.4 format

DSC parameter bits_per_pixel is stored in U6.4 format.
The 4 bits represent the fractional part of the bpp.
Currently we use compressed_bpp member of dsc structure to store
only the integral part of the bits_per_pixel.
To store the full bits_per_pixel along with the fractional part,
compressed_bpp is changed to store bpp in U6.4 formats. Intergral
part is retrieved by simply right shifting the member compressed_bpp by 4.

v2:
-Use to_bpp_int, to_bpp_frac_dec, to_bpp_x16 helpers while dealing
 with compressed bpp. (Suraj)
-Fix comment styling. (Suraj)

v3:
-Add separate file for 6.4 fixed point helper(Jani, Nikula)
-Add comment for magic values(Suraj)

v4:
-Fix checkpatch warnings caused by renaming(Suraj)

v5:
-Rebase.
-Use existing helpers for conversion of bpp_int to bpp_x16
 and vice versa.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Sui Jingfeng <suijingfeng@loongson.cn>
Link: https://patchwork.freedesktop.org/patch/msgid/20231110101020.4067342-3-ankit.k.nautiyal@intel.com

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_link_bw.c b/drivers/gpu/drm/i915/display/intel_link_bw.c
index 390db5c0c24a..02a0af2aa5ba 100644
--- a/drivers/gpu/drm/i915/display/intel_link_bw.c
+++ b/drivers/gpu/drm/i915/display/intel_link_bw.c
@@ -70,7 +70,7 @@ int intel_link_bw_reduce_bpp(struct intel_atomic_state *state,
 			return PTR_ERR(crtc_state);
 
 		if (crtc_state->dsc.compression_enable)
-			link_bpp = crtc_state->dsc.compressed_bpp;
+			link_bpp = crtc_state->dsc.compressed_bpp_x16;
 		else
 			/*
 			 * TODO: for YUV420 the actual link bpp is only half