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AJvYcCWwKdFfPHODdlGbqyQo6bUr8we1zuO0jEPAXC1Fe+oQsUOaw+Og8OSgyIXz9Uwa0S9vnpy8EfId72w1@vger.kernel.org X-Gm-Message-State: AOJu0YxWhNDjgCAvs2lbv59454//2HPsuF6BpwO5UPTGTTyFTW/hIJxw RLqxRwIG09A6YlYwQXUTQERfEJBb1NlJBIUmDpihN1CJOR91WOrYKmU2RjeQVvwEoDDeQkziQq0 2PeE5GXWuTbKrMs8JXfwVJRbP1qMITTY85Clc X-Google-Smtp-Source: AGHT+IF/exW7Z8cqHE69JpNvFhXfSFn/gK+3++BaPSqwc/mLNvI2MIZL+YrUa/fxP6y1gQB3mQOVrQuly8TPYna1emM= X-Received: by 2002:a05:600c:3d93:b0:42c:b0b0:513a with SMTP id 5b1f17b1804b1-42fc83dee2emr4432795e9.2.1728388778507; Tue, 08 Oct 2024 04:59:38 -0700 (PDT) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20241007135508.3143756-1-joychakr@google.com> <20241007135508.3143756-2-joychakr@google.com> <1bc2c476-9d7b-4c87-924b-ecaed0f721de@kernel.org> In-Reply-To: <1bc2c476-9d7b-4c87-924b-ecaed0f721de@kernel.org> From: Joy Chakraborty Date: Tue, 8 Oct 2024 17:29:23 +0530 Message-ID: Subject: Re: [PATCH 1/2] dt-bindings: usb: dwc3: Add binding for USB Gen2 de-emphasis To: Krzysztof Kozlowski Cc: Greg Kroah-Hartman , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Thinh Nguyen , Felipe Balbi , linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Oct 8, 2024 at 4:53=E2=80=AFPM Krzysztof Kozlowski wrote: > > On 08/10/2024 12:23, Joy Chakraborty wrote: > > On Mon, Oct 7, 2024 at 8:26=E2=80=AFPM Krzysztof Kozlowski wrote: > >> > >> On 07/10/2024 15:55, Joy Chakraborty wrote: > >>> PIPE4 spec defines an 18bit de-emphasis setting to be passed from > >>> controller to the PHY. > >>> TxDeemph[17:0] is split as [5:0] C-1, [11:6] C0, [17:12] C+1 for 3 ta= p > >>> filter used for USB Gen2(10GT/s). > >>> > >>> Signed-off-by: Joy Chakraborty > >>> --- > >>> Documentation/devicetree/bindings/usb/snps,dwc3.yaml | 12 ++++++++++= ++ > >>> 1 file changed, 12 insertions(+) > >>> > >>> diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/D= ocumentation/devicetree/bindings/usb/snps,dwc3.yaml > >>> index 1cd0ca90127d..a1f1bbcf1467 100644 > >>> --- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml > >>> +++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml > >>> @@ -190,6 +190,18 @@ properties: > >>> - 1 # -3.5dB de-emphasis > >>> - 2 # No de-emphasis > >>> > >>> + snps,tx_gen2_de_emphasis_quirk: > >> > >> No underscores. > > > > Ack, will fix it with a follow up patch. > > > >> > >>> + description: When set core will set Tx de-emphasis for USB Gen2 > >> > >> And why it cannot be implied by compatible? > > > > As per my understanding these are tuning coefficients for de-emphasis > > particular to a platform and not the dwc3 controller, hence should not > > be a controller compatible. > > Platforms must have specific compatible, so this should be implied by > compatible. Maybe I am using the word "platform" incorrectly here, what I understand is that the same controller(in a chip) when used on 2 different physical form factors might need different deemphasis coefficient values to be passed to its Phy. Someone could correct me from the USB link stand point if I am mistaken here. Thanks Joy > > > Similar to the property defined right above this definition which is > > from PIPE3 spec for USB Gen1. > > > Best regards, > Krzysztof >