Message ID | 20230925154059.837152-18-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State | Superseded |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 1qknis-00EHjd-RK; Mon, 25 Sep 2023 15:42:11 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233134AbjIYPmN (ORCPT <rfc822;mkrufky@linuxtv.org> + 1 other); Mon, 25 Sep 2023 11:42:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53446 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233109AbjIYPlx (ORCPT <rfc822;linux-media@vger.kernel.org>); Mon, 25 Sep 2023 11:41:53 -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 7E144CDD for <linux-media@vger.kernel.org>; Mon, 25 Sep 2023 08:41:25 -0700 (PDT) Received: by mail-wm1-x333.google.com with SMTP id 5b1f17b1804b1-4060b623e64so633745e9.0 for <linux-media@vger.kernel.org>; Mon, 25 Sep 2023 08:41:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1695656483; x=1696261283; 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=yKTR9FGAJbp1Nit0RKPxQtBceNed5p1nXP0aMRVoGew=; b=QrsVFyjBk4md7uG1N5IvQSP5V1erEytLEvYNHpgT3vyzTmh38XzPDdzehb+6E2LZXN w1D39S1mXoceUOlTWjRMW1YpKN8OaiqtYUVMjot9OEbOU1nwjcFd7+5kOoUL2/HCgmis aiD/537GtobJ2vJ3m30T4zbWWQFnkSeKmT6Wj2t/1mY3fLQcct55lk9FsMt1q3nxS0LM 3fcNHpk9kV6wAxvUXVWtEDwwN1xB2lNNltONrNZD3CaQtEnnIBu9gh35zUxwVRzU9nGY Ou5lubkYZ3CrkWqZ7JJmqmGl3iA0c5gxFi7C1tN68DySt2ltSPFI78OBQQQkNTAkH2Fk meaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695656483; x=1696261283; 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=yKTR9FGAJbp1Nit0RKPxQtBceNed5p1nXP0aMRVoGew=; b=cc+w8Mv3sVAXHwTDvNGr0JM3uuOPjhank5wzQt7oFfgGlCjGSnXazOfAUDTwbCe7xk rO/wEMkwiZ/tTVCd1AFzHmOfwhKfPcvtL8VRydAYrCjBAL9G9LdBGoVfAfDjDRv2rEUM Gg8r7cliUlv9s5tgjLKBA6Mdv6M9Kql/LNoJ1dA+aBr4AZ+/WmVqbK+hr6dDf/dxi6Dk zVVMavTiHLevZO+ib0klcQ8FOFjuY/HYSklOtWtEPU3TorfhOAY0qw47pG4LLCZRCrsj iT0rETlfZcgsiJ6xnfjf/4Wg3UfEyNnZs6jo3ODf1aoZjo+rUbURVib/DsjM5VX0y487 AiOg== X-Gm-Message-State: AOJu0YyKv6iqu61k+0pQEYrSV1oXmeOt8HbetGIDhFAOoz5eqFCTP23I iQtiTUEaA9rqJmcYjDQDAMJajw== X-Google-Smtp-Source: AGHT+IFoAhU5Cs0xvXPtG7uTV1iy0I3SOLFGewWZ+KZawkMRIs4+1nopiCEkRO25IW2QkypAJvnF3Q== X-Received: by 2002:a05:600c:11d2:b0:405:409e:1fcb with SMTP id b18-20020a05600c11d200b00405409e1fcbmr43234wmi.5.1695656483646; Mon, 25 Sep 2023 08:41:23 -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 m15-20020a7bca4f000000b003fe4548188bsm15206155wml.48.2023.09.25.08.41.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Sep 2023 08:41:23 -0700 (PDT) From: Bryan O'Donoghue <bryan.odonoghue@linaro.org> To: linux-arm-msm@vger.kernel.org, linux-media@vger.kernel.org, hverkuil@xs4all.nl, laurent.pinchart@ideasonboard.com, robert.foss@linaro.org, todor.too@gmail.com, agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org, mchehab@kernel.org, sakari.ailus@linux.intel.com, andrey.konovalov@linaro.org Cc: linux-kernel@vger.kernel.org, Bryan O'Donoghue <bryan.odonoghue@linaro.org> Subject: [PATCH v6 17/17] media: qcom: camss: Comment CSID dt_id field Date: Mon, 25 Sep 2023 16:40:59 +0100 Message-ID: <20230925154059.837152-18-bryan.odonoghue@linaro.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230925154059.837152-1-bryan.odonoghue@linaro.org> References: <20230925154059.837152-1-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. 25, 2023, 3:40 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 | 12 ++++++++++++
1 file changed, 12 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..791f27b18c394 100644 --- a/drivers/media/platform/qcom/camss/camss-csid-gen2.c +++ b/drivers/media/platform/qcom/camss/camss-csid-gen2.c @@ -352,6 +352,18 @@ static void __csid_configure_stream(struct csid_device *csid, u8 enable, u8 vc) phy_sel = csid->phy.csiphy_id; if (enable) { + /* + * DT_ID is a two bit bitfield that is concatenated with + * the four least significant bits of the six 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; if (tg->enabled) {