From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A66DE7A721; Wed, 24 Jan 2024 17:36:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706117807; cv=none; b=BavDTyqbxP4e0Z6y3yw9OhBCsv3QfdpIaLsy4h7kzzJzxhP+2EbAt5ZXnvEITMbcJOklLUF+dRAI1goxIAwiEklAmlsgGaEHHjK5LJ4Selg7JSvsUXGDATXa8Suyg0etMrZbgDzYP0xy2Gn8ggC8HAQ9UNlZJfoX1/e2YYTyMbk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706117807; c=relaxed/simple; bh=3QjO5uCSOpQMB1ILZjNIw1kPsnLX3nr9mMc6N4yRg+k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XTPc97pVeLXJFUGZPr91NoOLnoaMu00FZpmRBUjpR2hvdY1c8ob2FPAscN4FicVGi2ipyrZYPxr9QX8wLfKjqbpTB+rYoJ4NDP3Xr0jqZA/a4p5eftolpTHVAB1QR/bGrbDN3ppHp7xs3H4sBHzhKAnPbO7GO2yjIXKuk3dE2co= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tfHQT/4w; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tfHQT/4w" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CC9BC433C7; Wed, 24 Jan 2024 17:36:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706117807; bh=3QjO5uCSOpQMB1ILZjNIw1kPsnLX3nr9mMc6N4yRg+k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tfHQT/4wRpas5NbBh4dvRllcQgejipPwdW9F8UsLdv3WNhhuTuxoLRxU30t/usubJ dZAvB+HlbtIMsXE2q1Gpyl0l3n1QZFiGSNqt94Ev8wwAcmMbbrHrgfsoO7xBTbAV/j 4b9VZFH2yCt/Qa+1UQSCT4H93l7oeuFH+RU1S81A6ejzRaHh4Airspl9iy/WhPhTU8 VMDX343eg80HVv8Cw+SXgj/RhVjXqUEBqh0wnqQRnCG60hQ15ttKjMstgqOFiDQo7c E0yJLnz3S6x+hlq6lsdh0fZ8T2dU+G8q1yyU9zYtlwLbj8HR+RLBqliUY2UxOaQnlN FiUhAVBaQJwZg== Date: Wed, 24 Jan 2024 17:36:42 +0000 From: Conor Dooley To: Frank Li Cc: ran.wang_1@nxp.com, Greg Kroah-Hartman , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Felipe Balbi , "open list:USB SUBSYSTEM" , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , open list , mark.rutland@arm.com, pku.leo@gmail.com, sergei.shtylyov@cogentembedded.com Subject: Re: [PATCH 1/2] dt-bindings: usb: dwc3: Add snps,host-vbus-glitches avoiding vbus glitch Message-ID: <20240124-unclothed-dodgy-c78b1fffa752@spud> References: <20240119213130.3147517-1-Frank.Li@nxp.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0Uq4A7ICogxopmKU" Content-Disposition: inline In-Reply-To: <20240119213130.3147517-1-Frank.Li@nxp.com> --0Uq4A7ICogxopmKU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jan 19, 2024 at 04:31:28PM -0500, Frank Li wrote: > From: Ran Wang >=20 > When DWC3 is set to host mode by programming register DWC3_GCTL, VBUS > (or its control signal) will turn on immediately on related Root Hub > ports. Then the VBUS will be de-asserted for a little while during xhci > reset (conducted by xhci driver) for a little while and back to normal. >=20 > This VBUS glitch might cause some USB devices emuration fail if kernel > boot with them connected. One SW workaround which can fix this is to > program all PORTSC[PP] to 0 to turn off VBUS immediately after setting > host mode in DWC3 driver(per signal measurement result, it will be too > late to do it in xhci-plat.c or xhci.c). >=20 > Signed-off-by: Ran Wang > Reviewed-by: Peter Chen > Signed-off-by: Frank Li > --- > Documentation/devicetree/bindings/usb/snps,dwc3.yaml | 7 +++++++ > 1 file changed, 7 insertions(+) >=20 > diff --git a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml b/Docum= entation/devicetree/bindings/usb/snps,dwc3.yaml > index 203a1eb66691f..dbf272b76e0b5 100644 > --- a/Documentation/devicetree/bindings/usb/snps,dwc3.yaml > +++ b/Documentation/devicetree/bindings/usb/snps,dwc3.yaml > @@ -273,6 +273,13 @@ properties: > with an external supply. > type: boolean > =20 > + snps,host-vbus-glitches: > + description: > + When set, power off all Root Hub ports immediately after > + setting host mode to avoid vbus (negative) glitch happen in later > + xhci reset. And the vbus will back to 5V automatically when reset = done. > + type: boolean Why do we want to have a property for this at all? The commit message seems to describe a problem that's limited to specific configurations and appears to be somethng the driver should do unconditionally. Could you explain why this cannot be done unconditionally please? Thanks, Conor. > + > snps,is-utmi-l1-suspend: > description: > True when DWC3 asserts output signal utmi_l1_suspend_n, false when > --=20 > 2.34.1 >=20 --0Uq4A7ICogxopmKU Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZbFKqQAKCRB4tDGHoIJi 0nx/AQChEWeSmwbix3trVsvSb6aCXaoxtg2NUedV62nkNzkaXQD+Ll463rzca8jG QHuKwBLVhjTuY45xu/Mbvva5xvUwBwE= =xy2x -----END PGP SIGNATURE----- --0Uq4A7ICogxopmKU--