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 51B642405ED for ; Mon, 22 Dec 2025 08:49:21 +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=1766393362; cv=none; b=iDPxYA8v4RjjVbarYjgsRiVOk5bVqkbGrMx1njb72tGf1LErUp4/exd9Ph1jXxzqRUEQHqnyj8ILBL1889W4R3wEDbOzhlg2G44XFnCU1kptkLoDFxgdMQnXJuAhngCdojqHomkeiik7JE/kQ8xHpikmqgj3p4AZXtgREQm2mTw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766393362; c=relaxed/simple; bh=lGYe4SrAQ5Z8Ufdx+swBTt8GT+eQWM3pprHLNUV2L/Q=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=TCBDIzHk9c5k8WLnnUOUkTDcfb5ULwzelbv5EY/5ftsm1/0tuZ3gpCKZXdmOoRXhkEHWIdnR+fFtDXIreYEUQsA6mP4aCNZVPsE/TZCdyi+GePLZ3Ox1tbzoY9ob2G66qSH5EZi4gWAkAutpq1srYG/WPdqfpioGw05Q84vfttw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OlaqKPzv; 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="OlaqKPzv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 45D52C4CEF1; Mon, 22 Dec 2025 08:49:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766393361; bh=lGYe4SrAQ5Z8Ufdx+swBTt8GT+eQWM3pprHLNUV2L/Q=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=OlaqKPzvixpFd7kDcohzwTGk8qpczpdyA32gxkUkzI1De0tvRKxSCVrkz5afWH747 SHuHyridHxjSYUnvEZvttvn91cCYfA/lep4JbjHxgiRzjuylHeeQMR7gG8jf4ZHd9B fnSZjIUrYd4yBTUdA81bD2Rym9B6rmWd0SYeajSsao6g/MUUQpdHX17YVBPNqlib3H grFVOSpbmQKYMK1kX+hZxhy5e0xSJNGfA8k9CsWObmug8bSBbNuP/yDGRcOC5K+E15 QN+MotGgEg7m/ZWkmxbMrUbcUMbbRqVnld+/ZwLpJ2yuYFZXeMyyTillTbMdTyTpCn VamLdZO8eDTNw== Date: Mon, 22 Dec 2025 09:49:20 +0100 From: Niklas Cassel To: Krishna Chaitanya Chundru CC: Jingoo Han , Manivannan Sadhasivam , Lorenzo Pieralisi , =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= , Rob Herring , Bjorn Helgaas , Frank Li , Damien Le Moal , Koichiro Den , linux-pci@vger.kernel.org Subject: Re: [PATCH] PCI: dwc: ep: Cache MSI outbound iATU mapping User-Agent: Thunderbird for Android In-Reply-To: <712064a7-abb4-4cad-b6a6-b5c3a8faadea@oss.qualcomm.com> References: <20251210071358.2267494-2-cassel@kernel.org> <8e00bd1c-29ae-43fd-90e8-ea0943cb02b6@oss.qualcomm.com> <712064a7-abb4-4cad-b6a6-b5c3a8faadea@oss.qualcomm.com> Message-ID: <5254D564-D848-4112-8C91-A0621353CE0A@kernel.org> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 22 December 2025 09:42:50 CET, Krishna Chaitanya Chundru wrote: >> I guess we will need to come up with something else for the MSI-X case= =2E >>=20 >>=20 >>> Use the MSIX doorbell method which will not use iATU at all, >>> dw_pcie_ep_raise_msix_irq_doorbell()=2E >> AFAICT, right now, the only driver ever calling this function is: >> drivers/pci/controller/dwc/pci-layerscape-ep=2Ec >>=20 >> Are you suggesting that we somehow change all the other DWC based EPC >> drivers' =2Eraise_irq() callback to call dw_pcie_ep_raise_msix_irq_door= bell() >> instead of dw_pcie_ep_raise_msix_irq() for case PCI_IRQ_MSIX ? >Yes=2E >> That sounds like a big change that would need to be tested and verified >> for each DWC based EPC driver=2E >I agree, but this will be clean solution to avoid iATU for MSIX=2E I agree that this sounds like a nice solution for those platforms that can= use it=2E But, for platforms that might not be able to use this method (not sure if = this is possible with all versions of the DWC core), we probably still need to come up with some other solution to this problem= =2E It would also be nice with some solution that can be used until all driver= s have been converted=2E Kind regards, Niklas