Message ID | 20230907164410.36651-18-bryan.odonoghue@linaro.org (mailing list archive) |
---|---|
State | Superseded |
Headers |
Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from <linux-media-owner@vger.kernel.org>) id 1qeII0-00Fxfc-Dv; Thu, 07 Sep 2023 16:55:32 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244289AbjIGQrO (ORCPT <rfc822;mkrufky@linuxtv.org> + 1 other); Thu, 7 Sep 2023 12:47:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234922AbjIGQqx (ORCPT <rfc822;linux-media@vger.kernel.org>); Thu, 7 Sep 2023 12:46:53 -0400 Received: from mail-wm1-x333.google.com (mail-wm1-x333.google.com [IPv6:2a00:1450:4864:20::333]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DCD92125 for <linux-media@vger.kernel.org>; Thu, 7 Sep 2023 09:46:20 -0700 (PDT) Received: by mail-wm1-x333.google.com with SMTP id 5b1f17b1804b1-402cc6b8bedso13271075e9.1 for <linux-media@vger.kernel.org>; Thu, 07 Sep 2023 09:46:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1694105077; x=1694709877; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=FIu4eWCkEOSVtI8FoLJRLwwONGivM5mrULXtY5Z5HVI=; b=Zg6OBfUH4MExpnSfXQB3UVHFUUKI1ixC15c3XqL5WZQYf7FpAURcJgiicPUwFSPWW/ uGclQ0DZhVIdeOxNG9hHhUpSa/AokckeED6ffsXDxU3qe7wDUGVAPL+AMnk1pF+f7la3 rY2ckNU3ZY2Y3amh+5ghwswnX9LqVIpQDdKeB1VkHevANpGXiOHNQHPYOfzp3+1Ob61P 4AVQImJ41RKowwuM4L87uGGiTM4Mam3uw0pv/AhsVIj6CsyuGUd7AoSzq8rOpRAXB9VF bCs2DGj44UOkg9ckKD7B+LyQTSI70SLa5XXKJLwDyzZQ8tEAlPC3H53PVygCYuXQ8p0q sjnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1694105077; x=1694709877; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=FIu4eWCkEOSVtI8FoLJRLwwONGivM5mrULXtY5Z5HVI=; b=OaX/mQq9riEz2Z2nZNx7RksQn2ZTGpRgix/DKgTP25m2mJo7ymU9yx1JTiqyIJtDOR SvisbDSetIaGTeocz5/+XyCy/sQx4mQPlVvKd3IEnU6DDgH9FUPKWSf8TNziCaNmVloe zZRv4k8bCx+r5FECkI2oahMbitDifQpODc8EWrOgToCiaWcoCdbdfxcrH+FB/oUroqx4 VYsfsILpfMHLDztZbViaO0FGJPdcBKY6S1yTvzUlXDsIC1i30omMm7Nu+PjWHMLFu4ys l+K3KhVjoTH9ZoNf0zITB6mjT6ctklAF4HR+8KuhrNdTbY0FFhaBTodjUpdb+Bp+KJm4 /+UA== X-Gm-Message-State: AOJu0YypE4XvZZPR3MXVLzjWcZ58EA5KnCEtj8jHvhpUunO2XBibWxl6 OGQqROJqxdW7yeUpvauzuM9v/w== X-Google-Smtp-Source: AGHT+IHYQm/x1ttHvlb4nOLzsoqtQcWa1sflGXM/+Y5olsT43jMQsj+a+Uw0WpuUCkC0LtSmUtNegg== X-Received: by 2002:adf:d0ca:0:b0:317:e1fb:d56a with SMTP id z10-20020adfd0ca000000b00317e1fbd56amr5095651wrh.40.1694105077152; Thu, 07 Sep 2023 09:44:37 -0700 (PDT) Received: from sagittarius-a.chello.ie (188-141-3-169.dynamic.upc.ie. [188.141.3.169]) by smtp.gmail.com with ESMTPSA id d15-20020adffd8f000000b00317ab75748bsm23822145wrr.49.2023.09.07.09.44.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Sep 2023 09:44:36 -0700 (PDT) From: Bryan O'Donoghue <bryan.odonoghue@linaro.org> To: rfoss@kernel.org, todor.too@gmail.com, bryan.odonoghue@linaro.org, agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org, mchehab@kernel.org, hverkuil-cisco@xs4all.nl, laurent.pinchart@ideasonboard.com, sakari.ailus@linux.intel.com, andrey.konovalov@linaro.org Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 17/17] media: qcom: camss: Comment CSID dt_id field Date: Thu, 7 Sep 2023 17:44:10 +0100 Message-ID: <20230907164410.36651-18-bryan.odonoghue@linaro.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230907164410.36651-1-bryan.odonoghue@linaro.org> References: <20230907164410.36651-1-bryan.odonoghue@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: <linux-media.vger.kernel.org> X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -2.5 (--) X-LSpam-Report: No, score=-2.5 required=5.0 tests=BAYES_00=-1.9,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1 autolearn=ham autolearn_force=no |
Series |
media: qcom: camss: Add parameter passing to remove several outstanding bugs
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Commit Message
Bryan O'Donoghue
Sept. 7, 2023, 4:44 p.m. UTC
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>
---
drivers/media/platform/qcom/camss/camss-csid-gen2.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/media/platform/qcom/camss/camss-csid-gen2.c b/drivers/media/platform/qcom/camss/camss-csid-gen2.c index 6ba2b10326444..cee50fc87e9de 100644 --- a/drivers/media/platform/qcom/camss/camss-csid-gen2.c +++ b/drivers/media/platform/qcom/camss/camss-csid-gen2.c @@ -352,6 +352,11 @@ static void __csid_configure_stream(struct csid_device *csid, u8 enable, u8 vc) phy_sel = csid->phy.csiphy_id; if (enable) { + /* + * A value caled 'CID' gets generated internal to CAMSS logic + * which is a concatenation of [vc:6 | dt_id:2] hence we reuse + * the least significant two bits of the VC to 'stuff' the CID value. + */ u8 dt_id = vc; if (tg->enabled) {