From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A35F6C4727E for ; Thu, 1 Oct 2020 22:26:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A3272068E for ; Thu, 1 Oct 2020 22:26:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=broadcom.com header.i=@broadcom.com header.b="QSZGkLG2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731525AbgJAW0r (ORCPT ); Thu, 1 Oct 2020 18:26:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725924AbgJAW0p (ORCPT ); Thu, 1 Oct 2020 18:26:45 -0400 Received: from mail-pg1-x541.google.com (mail-pg1-x541.google.com [IPv6:2607:f8b0:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61A1AC0613D0 for ; Thu, 1 Oct 2020 15:26:45 -0700 (PDT) Received: by mail-pg1-x541.google.com with SMTP id m34so111562pgl.9 for ; Thu, 01 Oct 2020 15:26:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to; bh=dzHml+jwKeFJNXR2tTApwu496+pZFDv/DJiJ/AUcP+E=; b=QSZGkLG2wBts2uriXrgmKHi2zaCSAsSUqvLroqogrPwsOsncbxUgL23DEiVyNPtv6M Ik8nDReWhdmL/+GEIlVKJFN8TvkasrJhOyqrF5o1y3kXjP5jhV0wA9IhVTDIOp8NTrCU I/Puc1fJlgPLhFmo8LaWYU8VF7YNfPrAu+YR4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to; bh=dzHml+jwKeFJNXR2tTApwu496+pZFDv/DJiJ/AUcP+E=; b=ESQKhJTNA8zTRCWnR7dqwbiwwzGB5AZFKdXasQp8qopx0uQD5ONMZKePvR6erLX4cn exgB629HTXIA1Qh+UURgNSFgWa/MntUHSP9jou41wprMt7M3mGvl7ablzImd5ML0zJ+y CQFX4it/Gb1Lo6lQD+JzeT/2z+5ovFuQp3b4GNtypVvcLJLkKxX36WWMesP8vL704wp7 qJFCSfc0OUz1xBH98X6t/vr9+qWwSuFt/iiC8Ti2dWR9yHgbJzCu/9+JJqehrX+66E21 Rag2gouRJQTE+0zjlodXG8ynyCHXTQutyh39DsQakpte1beiK3aq0Kvadrtx8RSsblNr aJ0A== X-Gm-Message-State: AOAM532hqVPD6zreYBe+aSvn+MsDbZEFUH/Mw6fbb/MH32Cv1S0REve+ nX0BRVqyBeJHjnU3CU0IXn7S7Q== X-Google-Smtp-Source: ABdhPJzTDw+DVIFwXIIVc88l/FHG9L2oeASomGF0ZGUrvwiBTjAFp/Yhi8Lpn6TWKyF2Bat4sQ43Ew== X-Received: by 2002:a63:e655:: with SMTP id p21mr7819559pgj.420.1601591204713; Thu, 01 Oct 2020 15:26:44 -0700 (PDT) Received: from [10.136.13.65] ([192.19.228.250]) by smtp.gmail.com with ESMTPSA id h5sm829459pja.55.2020.10.01.15.26.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 01 Oct 2020 15:26:44 -0700 (PDT) Subject: Re: [PATCH v5 15/15] misc: bcm-vk: add ttyVK support To: Florian Fainelli , Arnd Bergmann , Greg Kroah-Hartman , Olof Johansson Cc: Kees Cook , linux-kernel@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com References: <20201001012810.4172-1-scott.branden@broadcom.com> <20201001012810.4172-16-scott.branden@broadcom.com> <278afb05-8c8d-98d2-eed0-f73b954b03c7@gmail.com> From: Scott Branden Message-ID: <140a5cde-67fd-f4b1-e4a9-9c68adf964c4@broadcom.com> Date: Thu, 1 Oct 2020 15:26:41 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <278afb05-8c8d-98d2-eed0-f73b954b03c7@gmail.com> Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="000000000000dc278a05b0a38256" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --000000000000dc278a05b0a38256 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-CA Hi Florian, On 2020-09-30 7:36 p.m., Florian Fainelli wrote: > > > On 9/30/2020 6:28 PM, Scott Branden wrote: >> Add ttyVK support to driver to allow console access to VK card from host. >> >> Device node will be in the follow form /dev/bcm-vk.x_ttyVKy where: >> x is the instance of the VK card >> y is the tty device number on the VK card >> >> Signed-off-by: Scott Branden > > Was it not possible to: > > - emulate a standard 8250 UART and just expose an additional bar + MSI vector such that one could get a debug UART out of this device with little to no work on the host side? I don't see how such emulation is simpler than what we have.  For a standard 8250 UART implementation how would we emulate a FIFO in memory accessible over PCIe.  I don't see how to do that with shared memory?  Also, we don't have an additional bar available on the PCIe device.  There is currently little to no work on the device side using a circular buffer with read and write pointers. > > - or use virtio console and implement virtio on the firmware that runs on VK? Not that possible as the debug/console UARTs are used inside and outside of linux on the VK card. > > It's not a lot of code, but it just feels like this should not have to be done at all. If there was a simpler way to do it, yes, I would like a "UART" running over PCIe shared memory via a circular buffer. And that is what the code we developed does. --000000000000dc278a05b0a38256 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIIQRQYJKoZIhvcNAQcCoIIQNjCCEDICAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg gg2aMIIE6DCCA9CgAwIBAgIOSBtqCRO9gCTKXSLwFPMwDQYJKoZIhvcNAQELBQAwTDEgMB4GA1UE CxMXR2xvYmFsU2lnbiBSb290IENBIC0gUjMxEzARBgNVBAoTCkdsb2JhbFNpZ24xEzARBgNVBAMT Ckdsb2JhbFNpZ24wHhcNMTYwNjE1MDAwMDAwWhcNMjQwNjE1MDAwMDAwWjBdMQswCQYDVQQGEwJC RTEZMBcGA1UEChMQR2xvYmFsU2lnbiBudi1zYTEzMDEGA1UEAxMqR2xvYmFsU2lnbiBQZXJzb25h bFNpZ24gMiBDQSAtIFNIQTI1NiAtIEczMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA tpZok2X9LAHsYqMNVL+Ly6RDkaKar7GD8rVtb9nw6tzPFnvXGeOEA4X5xh9wjx9sScVpGR5wkTg1 fgJIXTlrGESmaqXIdPRd9YQ+Yx9xRIIIPu3Jp/bpbiZBKYDJSbr/2Xago7sb9nnfSyjTSnucUcIP ZVChn6hKneVGBI2DT9yyyD3PmCEJmEzA8Y96qT83JmVH2GaPSSbCw0C+Zj1s/zqtKUbwE5zh8uuZ p4vC019QbaIOb8cGlzgvTqGORwK0gwDYpOO6QQdg5d03WvIHwTunnJdoLrfvqUg2vOlpqJmqR+nH 9lHS+bEstsVJtZieU1Pa+3LzfA/4cT7XA/pnwwIDAQABo4IBtTCCAbEwDgYDVR0PAQH/BAQDAgEG MGoGA1UdJQRjMGEGCCsGAQUFBwMCBggrBgEFBQcDBAYIKwYBBQUHAwkGCisGAQQBgjcUAgIGCisG AQQBgjcKAwQGCSsGAQQBgjcVBgYKKwYBBAGCNwoDDAYIKwYBBQUHAwcGCCsGAQUFBwMRMBIGA1Ud EwEB/wQIMAYBAf8CAQAwHQYDVR0OBBYEFGlygmIxZ5VEhXeRgMQENkmdewthMB8GA1UdIwQYMBaA FI/wS3+oLkUkrk1Q+mOai97i3Ru8MD4GCCsGAQUFBwEBBDIwMDAuBggrBgEFBQcwAYYiaHR0cDov L29jc3AyLmdsb2JhbHNpZ24uY29tL3Jvb3RyMzA2BgNVHR8ELzAtMCugKaAnhiVodHRwOi8vY3Js Lmdsb2JhbHNpZ24uY29tL3Jvb3QtcjMuY3JsMGcGA1UdIARgMF4wCwYJKwYBBAGgMgEoMAwGCisG AQQBoDIBKAowQQYJKwYBBAGgMgFfMDQwMgYIKwYBBQUHAgEWJmh0dHBzOi8vd3d3Lmdsb2JhbHNp Z24uY29tL3JlcG9zaXRvcnkvMA0GCSqGSIb3DQEBCwUAA4IBAQConc0yzHxn4gtQ16VccKNm4iXv 6rS2UzBuhxI3XDPiwihW45O9RZXzWNgVcUzz5IKJFL7+pcxHvesGVII+5r++9eqI9XnEKCILjHr2 DgvjKq5Jmg6bwifybLYbVUoBthnhaFB0WLwSRRhPrt5eGxMw51UmNICi/hSKBKsHhGFSEaJQALZy 4HL0EWduE6ILYAjX6BSXRDtHFeUPddb46f5Hf5rzITGLsn9BIpoOVrgS878O4JnfUWQi29yBfn75 HajifFvPC+uqn+rcVnvrpLgsLOYG/64kWX/FRH8+mhVe+mcSX3xsUpcxK9q9vLTVtroU/yJUmEC4 OcH5dQsbHBqjMIIDXzCCAkegAwIBAgILBAAAAAABIVhTCKIwDQYJKoZIhvcNAQELBQAwTDEgMB4G A1UECxMXR2xvYmFsU2lnbiBSb290IENBIC0gUjMxEzARBgNVBAoTCkdsb2JhbFNpZ24xEzARBgNV BAMTCkdsb2JhbFNpZ24wHhcNMDkwMzE4MTAwMDAwWhcNMjkwMzE4MTAwMDAwWjBMMSAwHgYDVQQL ExdHbG9iYWxTaWduIFJvb3QgQ0EgLSBSMzETMBEGA1UEChMKR2xvYmFsU2lnbjETMBEGA1UEAxMK R2xvYmFsU2lnbjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMwldpB5BngiFvXAg7aE yiie/QV2EcWtiHL8RgJDx7KKnQRfJMsuS+FggkbhUqsMgUdwbN1k0ev1LKMPgj0MK66X17YUhhB5 uzsTgHeMCOFJ0mpiLx9e+pZo34knlTifBtc+ycsmWQ1z3rDI6SYOgxXG71uL0gRgykmmKPZpO/bL yCiR5Z2KYVc3rHQU3HTgOu5yLy6c+9C7v/U9AOEGM+iCK65TpjoWc4zdQQ4gOsC0p6Hpsk+QLjJg 6VfLuQSSaGjlOCZgdbKfd/+RFO+uIEn8rUAVSNECMWEZXriX7613t2Saer9fwRPvm2L7DWzgVGkW qQPabumDk3F2xmmFghcCAwEAAaNCMEAwDgYDVR0PAQH/BAQDAgEGMA8GA1UdEwEB/wQFMAMBAf8w HQYDVR0OBBYEFI/wS3+oLkUkrk1Q+mOai97i3Ru8MA0GCSqGSIb3DQEBCwUAA4IBAQBLQNvAUKr+ yAzv95ZURUm7lgAJQayzE4aGKAczymvmdLm6AC2upArT9fHxD4q/c2dKg8dEe3jgr25sbwMpjjM5 RcOO5LlXbKr8EpbsU8Yt5CRsuZRj+9xTaGdWPoO4zzUhw8lo/s7awlOqzJCK6fBdRoyV3XpYKBov Hd7NADdBj+1EbddTKJd+82cEHhXXipa0095MJ6RMG3NzdvQXmcIfeg7jLQitChws/zyrVQ4PkX42 68NXSb7hLi18YIvDQVETI53O9zJrlAGomecsMx86OyXShkDOOyyGeMlhLxS67ttVb9+E7gUJTb0o 2HLO02JQZR7rkpeDMdmztcpHWD9fMIIFRzCCBC+gAwIBAgIMW0PXrlFB5QLwO+gIMA0GCSqGSIb3 DQEBCwUAMF0xCzAJBgNVBAYTAkJFMRkwFwYDVQQKExBHbG9iYWxTaWduIG52LXNhMTMwMQYDVQQD EypHbG9iYWxTaWduIFBlcnNvbmFsU2lnbiAyIENBIC0gU0hBMjU2IC0gRzMwHhcNMjAwOTIxMTQz MTE0WhcNMjIwOTIyMTQzMTE0WjCBkDELMAkGA1UEBhMCSU4xEjAQBgNVBAgTCUthcm5hdGFrYTES MBAGA1UEBxMJQmFuZ2Fsb3JlMRYwFAYDVQQKEw1Ccm9hZGNvbSBJbmMuMRYwFAYDVQQDEw1TY290 dCBCcmFuZGVuMSkwJwYJKoZIhvcNAQkBFhpzY290dC5icmFuZGVuQGJyb2FkY29tLmNvbTCCASIw DQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBALCwcSIu11LCx3EwXsMF/0Te79hG0UI3NZAsVxAh exVD4CJDTVDgpCWOXj2j4V0eOvFYcGgMNVUKtywL4OzQgNquS8/OlHQZ3/9PCq8Ox9PNkCQ5eIv1 k2UaaN0tMDke1fX++Dn0UXst0OI08PYKYJpy1mkw5Hcw28LxU5Q2HwoW/+gyOIkdSo2ovq7a9+G3 LGyQOUxLhMvko/+qqg/KTfYQJ45p6TJPcvzwA0W453P3gPRZpm54KsEIfyZiMaUBMtXsQ7dHBAla I/3RRboOeC9M13VNr5feU91O0iDoMreAgPQJ0Lo7YrodKYug0Tt/fFDjkW3v3VIbEr2liUN69U0C AwEAAaOCAdEwggHNMA4GA1UdDwEB/wQEAwIFoDCBngYIKwYBBQUHAQEEgZEwgY4wTQYIKwYBBQUH MAKGQWh0dHA6Ly9zZWN1cmUuZ2xvYmFsc2lnbi5jb20vY2FjZXJ0L2dzcGVyc29uYWxzaWduMnNo YTJnM29jc3AuY3J0MD0GCCsGAQUFBzABhjFodHRwOi8vb2NzcDIuZ2xvYmFsc2lnbi5jb20vZ3Nw ZXJzb25hbHNpZ24yc2hhMmczME0GA1UdIARGMEQwQgYKKwYBBAGgMgEoCjA0MDIGCCsGAQUFBwIB FiZodHRwczovL3d3dy5nbG9iYWxzaWduLmNvbS9yZXBvc2l0b3J5LzAJBgNVHRMEAjAAMEQGA1Ud HwQ9MDswOaA3oDWGM2h0dHA6Ly9jcmwuZ2xvYmFsc2lnbi5jb20vZ3NwZXJzb25hbHNpZ24yc2hh MmczLmNybDAlBgNVHREEHjAcgRpzY290dC5icmFuZGVuQGJyb2FkY29tLmNvbTATBgNVHSUEDDAK BggrBgEFBQcDBDAfBgNVHSMEGDAWgBRpcoJiMWeVRIV3kYDEBDZJnXsLYTAdBgNVHQ4EFgQUWOK7 qiyDSt/IDm/SRcNi/sTEiyswDQYJKoZIhvcNAQELBQADggEBAEe2edd4F9tpp0GPmrFrQ+xp9kY7 uxBzPdCw588bgVrPemjLwiwV37XTT4iWJtNhPfEpaguM6jeLm58LCvHq5/IBjcyHyf4URQVwAg7B pqkH8/M+IBstu4/D+znPHB59X+c+au3Q8D+xoNFd7I30kaE+oJuBuFsGXRBc0Ci+FM86x9k7SF8U aui1E7Y9wDfsRSCL2TSwU773f09WkrvVdlKxNqQZj2z7bQUUn+yfXdFfBz0LqlYNfn7xJOpQE3HI H4jq6U9+b0Qf+J0n0wyysjXPSeQ7EKXVkT8dM2KSpIN86v5dd9LkAz3C1dmjuPRGEC8ZhI1IjMBt 0itrn6C23NsxggJvMIICawIBATBtMF0xCzAJBgNVBAYTAkJFMRkwFwYDVQQKExBHbG9iYWxTaWdu IG52LXNhMTMwMQYDVQQDEypHbG9iYWxTaWduIFBlcnNvbmFsU2lnbiAyIENBIC0gU0hBMjU2IC0g RzMCDFtD165RQeUC8DvoCDANBglghkgBZQMEAgEFAKCB1DAvBgkqhkiG9w0BCQQxIgQg1QsVX6l0 xXqR0n0cgVEOZn7sdLd13GN3zu/7Gkoftf0wGAYJKoZIhvcNAQkDMQsGCSqGSIb3DQEHATAcBgkq hkiG9w0BCQUxDxcNMjAxMDAxMjIyNjQ1WjBpBgkqhkiG9w0BCQ8xXDBaMAsGCWCGSAFlAwQBKjAL BglghkgBZQMEARYwCwYJYIZIAWUDBAECMAoGCCqGSIb3DQMHMAsGCSqGSIb3DQEBCjALBgkqhkiG 9w0BAQcwCwYJYIZIAWUDBAIBMA0GCSqGSIb3DQEBAQUABIIBAFL+HYCLSKP2V9dL3OyQURTKDq+j wGmQ18EADMUd5j+JXxBP1xVtImOq4OuqRnUUlMS9ey3Q0AAo1xLKwkWht6XV9zkChwVPCSp5Otzz aQyUpThDyAlNzNiRiuM99qSb9xYRgQfhU6aynldAVpggGz+SJt7NnuN9QlWVlBNSxS9xeNNtGwd8 bxIBzZhoZDIHM4D5YULn8UDx44VGHSBjetCMZ5X/2uQzm/RIAPW9CbsyuIhINc6+UfyIbqS0atXu UPjpcHyWbB8NHAniL5YZEnGzTl+1ZteSLpKPFtm8cb8QEINUhWhDKCpefnWvHJ0mqgVLMniJfyvD qFPEUdR2aOE= --000000000000dc278a05b0a38256--