6.6-stable patches

added patches:
	media-qcom-camss-comment-csid-dt_id-field.patch

diff --git a/queue-6.6/media-qcom-camss-comment-csid-dt_id-field.patch b/queue-6.6/media-qcom-camss-comment-csid-dt_id-field.patch
new file mode 100644 (file)
index 0000000..411c667
--- /dev/null
+++ b/queue-6.6/media-qcom-camss-comment-csid-dt_id-field.patch
@@ -0,0 +1,61 @@
+From f910d3ba78a2677c23508f225eb047d89eb4b2b6 Mon Sep 17 00:00:00 2001
+From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
+Date: Thu, 28 Sep 2023 01:58:25 +0100
+Subject: media: qcom: camss: Comment CSID dt_id field
+
+From: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
+
+commit f910d3ba78a2677c23508f225eb047d89eb4b2b6 upstream.
+
+Digging into the documentation we find that the DT_ID bitfield is used to
+map the six bit DT to a two bit ID code. This value is concatenated to the
+VC bitfield to create a CID value. DT_ID is the two least significant bits
+of CID and VC the most significant bits.
+
+Originally we set dt_id = vc * 4 in and then subsequently set dt_id = vc.
+
+commit 3c4ed72a16bc ("media: camss: sm8250: Virtual channels for CSID")
+silently fixed the multiplication by four which would give a better
+value for the generated CID without mentioning what was being done or why.
+
+Next up I haplessly changed the value back to "dt_id = vc * 4" since there
+didn't appear to be any logic behind it.
+
+Hans asked what the change was for and I honestly couldn't remember the
+provenance of it, so I dug in.
+
+Link: https://lore.kernel.org/linux-arm-msm/edd4bf9b-0e1b-883c-1a4d-50f4102c3924@xs4all.nl/
+
+Add a comment so the next hapless programmer doesn't make this same
+mistake.
+
+Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
+Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/media/platform/qcom/camss/camss-csid-gen2.c |   14 +++++++++++++-
+ 1 file changed, 13 insertions(+), 1 deletion(-)
+
+--- a/drivers/media/platform/qcom/camss/camss-csid-gen2.c
++++ b/drivers/media/platform/qcom/camss/camss-csid-gen2.c
+@@ -352,7 +352,19 @@ static void __csid_configure_stream(stru
+               phy_sel = csid->phy.csiphy_id;
+ 
+       if (enable) {
+-              u8 dt_id = vc;
++              /*
++               * DT_ID is a two bit bitfield that is concatenated with
++               * the four least significant bits of the five bit VC
++               * bitfield to generate an internal CID value.
++               *
++               * CSID_RDI_CFG0(vc)
++               * DT_ID : 28:27
++               * VC    : 26:22
++               * DT    : 21:16
++               *
++               * CID   : VC 3:0 << 2 | DT_ID 1:0
++               */
++              u8 dt_id = vc & 0x03;
+ 
+               if (tg->enabled) {
+                       /* configure one DT, infinite frames */

diff --git a/queue-6.6/series b/queue-6.6/series
index d53bc2bcdc366809df0ad9c635f8d42e01c7b7b1..f24beb9afba5d030e920709e4bc8cef7a1912659 100644 (file)
--- a/queue-6.6/series
+++ b/queue-6.6/series
@@ -121,3 +121,4 @@ mmc-sdhci-sprd-fix-emmc-init-failure-after-hw-reset.patch
 cxl-add-cxl_num_decoders_committed-usage-to-cxl_test.patch
 cxl-hdm-fix-a-benign-lockdep-splat.patch
 cxl-memdev-hold-region_rwsem-during-inject-and-clear-poison-ops.patch
+media-qcom-camss-comment-csid-dt_id-field.patch