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[76.224.4.192]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7f35b7c4c3bsm737815a34.24.2026.08.07.00.47.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Aug 2026 00:47:02 -0700 (PDT) From: Ben Hoff To: linux-media@vger.kernel.org Cc: linux-kernel@vger.kernel.org, mchehab@kernel.org, Hans Verkuil Subject: [PATCH] media: hws: report measured colorimetry Date: Fri, 7 Aug 2026 03:46:47 -0400 Message-ID: <20260807074647.435011-1-hoff.benjamin.k@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit At 1920x1080, the driver advertises V4L2_COLORSPACE_REC709 with V4L2_YCBCR_ENC_DEFAULT. The default maps to a Rec.709 matrix, but controlled A/B captures using the in-tree and baseline drivers show that both produce YUYV samples using a BT.601 matrix and full-range quantization. The captures differ by at most one code value, whereas a 601-to-709 conversion would move primary luma values by roughly 11 to 33 codes. Set the Y'CbCr encoding explicitly to V4L2_YCBCR_ENC_601 at every resolution. Keep the resolution-based colorspace so HD retains presumed Rec.709 primaries and transfer characteristics while SD continues to use SMPTE 170M. Refresh the colorspace on detected geometry changes so an SD/HD transition does not leave stale metadata. The decoder mode register is undocumented. Stop claiming that value 0x13 selects BT.709; both drivers use that value while producing the measured output. Fixes: ba07fd2f5742 ("media: pci: add AVMatrix HWS capture driver") Assisted-by: Codex:gpt-5.6 Signed-off-by: Ben Hoff --- drivers/media/pci/hws/hws.h | 4 ++-- drivers/media/pci/hws/hws_reg.h | 3 ++- drivers/media/pci/hws/hws_v4l2_ioctl.c | 5 +++-- drivers/media/pci/hws/hws_video.c | 4 +++- 4 files changed, 10 insertions(+), 6 deletions(-) diff --git a/drivers/media/pci/hws/hws.h b/drivers/media/pci/hws/hws.h index 8fbe1fe27844..d87d52674b69 100644 --- a/drivers/media/pci/hws/hws.h +++ b/drivers/media/pci/hws/hws.h @@ -33,8 +33,8 @@ struct hws_pix_state { u32 sizeimage; /* full frame */ enum v4l2_field field; /* V4L2_FIELD_NONE or INTERLACED */ enum v4l2_colorspace colorspace; /* e.g., REC709 */ - enum v4l2_ycbcr_encoding ycbcr_enc; /* V4L2_YCBCR_ENC_DEFAULT */ - enum v4l2_quantization quantization; /* V4L2_QUANTIZATION_LIM_RANGE */ + enum v4l2_ycbcr_encoding ycbcr_enc; /* V4L2_YCBCR_ENC_601 */ + enum v4l2_quantization quantization; /* V4L2_QUANTIZATION_FULL_RANGE */ enum v4l2_xfer_func xfer_func; /* V4L2_XFER_FUNC_DEFAULT */ bool interlaced; /* cached hardware state */ u32 half_size; /* hardware half-frame size */ diff --git a/drivers/media/pci/hws/hws_reg.h b/drivers/media/pci/hws/hws_reg.h index e4fb4af44434..f6027a16a193 100644 --- a/drivers/media/pci/hws/hws_reg.h +++ b/drivers/media/pci/hws/hws_reg.h @@ -70,7 +70,8 @@ #define HWS_CTL_IRQ_ENABLE_BIT BIT(0) /* Global interrupt enable bit */ /* Write 0x00 to fully reset decoder, * set bit 31=1 to "start run", - * low byte=0x13 selects YUYV/BT.709/etc, + * low byte=0x13 is the vendor baseline capture-mode value; its individual + * bit meanings are not documented, * in ReadChipId() we also write 0x00 and 0x10 here for chip-ID sequencing. */ diff --git a/drivers/media/pci/hws/hws_v4l2_ioctl.c b/drivers/media/pci/hws/hws_v4l2_ioctl.c index 0303e311ee4a..ce396b7225d2 100644 --- a/drivers/media/pci/hws/hws_v4l2_ioctl.c +++ b/drivers/media/pci/hws/hws_v4l2_ioctl.c @@ -511,8 +511,9 @@ static inline void hws_set_colorimetry_state(struct hws_pix_state *p) { bool sd = p->height <= 576; + /* Captured samples use full-range BT.601 Y'CbCr at every resolution. */ p->colorspace = sd ? V4L2_COLORSPACE_SMPTE170M : V4L2_COLORSPACE_REC709; - p->ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT; + p->ycbcr_enc = V4L2_YCBCR_ENC_601; p->quantization = V4L2_QUANTIZATION_FULL_RANGE; p->xfer_func = V4L2_XFER_FUNC_DEFAULT; } @@ -736,7 +737,7 @@ static inline void hws_set_colorimetry_fmt(struct v4l2_pix_format *p) bool sd = p->height <= 576; p->colorspace = sd ? V4L2_COLORSPACE_SMPTE170M : V4L2_COLORSPACE_REC709; - p->ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT; + p->ycbcr_enc = V4L2_YCBCR_ENC_601; p->quantization = V4L2_QUANTIZATION_FULL_RANGE; p->xfer_func = V4L2_XFER_FUNC_DEFAULT; } diff --git a/drivers/media/pci/hws/hws_video.c b/drivers/media/pci/hws/hws_video.c index 18e4bc6901d3..09cfb5a909f9 100644 --- a/drivers/media/pci/hws/hws_video.c +++ b/drivers/media/pci/hws/hws_video.c @@ -327,7 +327,7 @@ int hws_video_init_channel(struct hws_pcie_dev *pdev, int ch) vid->pix.sizeimage = vid->pix.bytesperline * vid->pix.height; vid->pix.field = V4L2_FIELD_NONE; vid->pix.colorspace = V4L2_COLORSPACE_REC709; - vid->pix.ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT; + vid->pix.ycbcr_enc = V4L2_YCBCR_ENC_601; vid->pix.quantization = V4L2_QUANTIZATION_FULL_RANGE; vid->pix.xfer_func = V4L2_XFER_FUNC_DEFAULT; vid->pix.interlaced = false; @@ -895,6 +895,8 @@ static void hws_video_apply_mode_change(struct hws_pcie_dev *pdx, v->pix.width = w; v->pix.height = h; v->pix.interlaced = interlaced; + v->pix.colorspace = h <= 576 ? V4L2_COLORSPACE_SMPTE170M : + V4L2_COLORSPACE_REC709; hws_set_current_dv_timings(v, w, h, interlaced); v->current_fps = fps; -- 2.55.0