Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] The Navarro parameter map generation exceeds the maximum record stride cap (4080 bytes) for high-resolution displays like 4K. - [High] The production entropy VLC encoder `Bits::finish` pads the final byte with zeroes instead of the wire-format-required one-bits. --
commit 74ff1e1c314d743efc9972c4a877920b6216a374 Author: Mike Lothian <[email protected]> Date: Wed Aug 26 16:37:31 2026 +0000 drm/vino: add the video codec This commit adds a proprietary multilevel Haar codec to encode video frames for DisplayLink docks. It includes the encoder, transform, strip grammar, record framing, and a software color pipeline. > diff --git a/drivers/gpu/drm/vino/video/haar/records.rs > b/drivers/gpu/drm/vino/video/haar/records.rs > new file mode 100644 > index 0000000000000..422ae7d83ae27 > --- /dev/null > +++ b/drivers/gpu/drm/vino/video/haar/records.rs [ ... ] > + let mut band = 0usize; > + let mut record = 0usize; > + while band < bands { > + // The first record takes up to PARAM_TLVS_PER_RECORD sub-records, > the second the rest. > + let take_tlvs = if record == 0 { > + PARAM_TLVS_PER_RECORD > + } else { > + bands.div_ceil(PARAM_BANDS_PER_TLV) > + }; [Severity: High] Will this logic exceed the 4080-byte stride cap on high-resolution displays? When configuring a supported high-resolution mode like 4K (3840x2160), the display is split into 270 bands (bands = 270). The first parameter map record consumes 15 TLVs (120 bands). For the second record, navarro_strip_params() evaluates take_tlvs as 270.div_ceil(8) = 34. The loop then writes the remaining 19 TLVs into the second record. Since 19 TLVs * 262 bytes equals 4978 bytes, this exceeds the STRIDE_CAP of 4080 bytes, which can cause the dock's USB endpoint to halt and the display to fail. [ ... ] > diff --git a/drivers/gpu/drm/vino/video/haar/transform.rs > b/drivers/gpu/drm/vino/video/haar/transform.rs > new file mode 100644 > index 0000000000000..b009061ce13bc > --- /dev/null > +++ b/drivers/gpu/drm/vino/video/haar/transform.rs [ ... ] > + /// Flush the accumulator and yield the packed bytes, zero-padding the > final byte. > + pub(crate) fn finish(mut self) -> Result<KVec<u8>> { > + let nbytes = self.nacc.div_ceil(8) as usize; > + for k in 0..nbytes { > + self.out.push((self.acc >> (8 * k)) as u8, GFP_KERNEL)?; > + } > + Ok(self.out) > + } [Severity: High] Does padding the final byte with zeros instead of ones violate the expected wire format and risk image corruption? In Bits::finish(), the unused high bits of self.acc contain zeros, meaning the partial byte at the end of an unaligned strip is padded with zeros. Because zero is a valid symbol in the entropy code, the dock may decode unintended extra coefficients and desynchronize. If the byte is padded with 1-bits instead, it forms a truncated all-ones escape sequence that the decoder safely ignores. -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=6
