From owner-freebsd-arm@freebsd.org Fri Sep 30 02:29:08 2016 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A4605C02484 for ; Fri, 30 Sep 2016 02:29:08 +0000 (UTC) (envelope-from embaudarm@gmail.com) Received: from mail-qk0-x22e.google.com (mail-qk0-x22e.google.com [IPv6:2607:f8b0:400d:c09::22e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5EE351A7B for ; Fri, 30 Sep 2016 02:29:08 +0000 (UTC) (envelope-from embaudarm@gmail.com) Received: by mail-qk0-x22e.google.com with SMTP id n189so22277909qke.0 for ; Thu, 29 Sep 2016 19:29:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=lt7XdQQo85Bfx5fnu21/6HmBZeL80EjEqhmS6WRmgM8=; b=opoYAYyJumFvZ8LH1q/iH6S7BZee8XCd/+rdricu7Fu8gIYPMpgkg9BrJ8N4u8gXxG NOL4do1Tbi5omYSjMOIlT0PH9Gwus6nN/I6fuL7PLL8tSLHC1FOScnOwpFv7zXTyT04w /+KH2BrutU8IY5PUwazVZB74UG3XjkVRFsbxDinDheV50TcLTvyb8h1qipxYwrqdP8Jo zaTJWVLhaKf97+cthHqouCT5kWsnJ27Qm5kef8xA9wwYiBiyen7YaIxc5MN60u4kNDi1 r8zq22fJn1ogeDHkG6Vhmi2mZki/C2T16zOGk08oo+ILV0sBbsvp7CFXDhVf/bwsGWxj eQuw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=lt7XdQQo85Bfx5fnu21/6HmBZeL80EjEqhmS6WRmgM8=; b=K0mH3E2JGWj7dYfJ0V+2OCejYw7U/vRX2o1LbugLU/xi/H+KpDwrqzjZeTX5aFnGdP +Npz8xVvOn+JJuPI9qCnOp9zfkewsl1n7Ug4gSUW+joPs7MVACvn7DKBK8ROz0VxdSgN /hOjvZNPNfGJPdtbj0nQYV454rFXByP/2R9QEiB6yt+kcRbdFLflQm+Npo/NaoygPV56 jr8Sv+18s0pCahkxgFasA6dcwtASOpR9JR2kx44oKGxFOXqT/9uF/eyO4NwhaLdwA73b 8wa+oDdBlA1B1/e41JQTJfPuWQQBCCN1BB6/sKNKQ1GyFQDxH7i0CPg1NrnPgkZFIc9R wBSg== X-Gm-Message-State: AA6/9RmMhRpRrLinvFUBWKBsEdAZa54ihFjpBfAjAN277esJ+KYSmUQfl0fqF6e4tc7g5Iv/vb1irmAxtgRWDg== X-Received: by 10.55.104.199 with SMTP id d190mr4825572qkc.163.1475202547651; Thu, 29 Sep 2016 19:29:07 -0700 (PDT) MIME-Version: 1.0 Received: by 10.200.42.194 with HTTP; Thu, 29 Sep 2016 19:29:07 -0700 (PDT) In-Reply-To: <02E012FA-342E-4EB7-99F2-733FA7990BDD@yahoo.com> References: <02E012FA-342E-4EB7-99F2-733FA7990BDD@yahoo.com> From: Lee D Date: Thu, 29 Sep 2016 22:29:07 -0400 Message-ID: Subject: Re: SD-Card driver modification for Zynq questions To: Thomas Skibo Cc: freebsd-arm Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 30 Sep 2016 02:29:08 -0000 On Wed, Sep 28, 2016 at 10:16 AM, Thomas Skibo wrote: > > Why not just set max-frequency to 200Mhz in the DTS file entry? > > =E2=80=94=E2=80=94 > Thomas Skibo > thomasskibo@yahoo.com > > I hadn't thought of that. I think you are suggesting that I tell the driver that the clock speed is higher than it is so all of the clock divisors are set higher, which would result in a lower data rate. That's a clever idea, but I think I would actually have to set the max-frequency to 500MHz, since some cards are capable of operating up to 100MHz and my SD-Card slot can only run (safely) at 20MHz. That means at that all normal 25MHz cards would run dramatically slower than they need to. In the event that I can't figure out how to make a new DTS file parameter for max data rate, do you think that my modification is a decent way to accomplish my goal? Thanks, Lee