Date: Wed, 10 Apr 2013 10:21:27 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Ian Lepore <ian@freebsd.org> Cc: Aleksandr Rybalko <ray@freebsd.org>, Dmytro <dioptimizer@gmail.com>, freebsd-mips@freebsd.org Subject: Re: [PATCH] MMC/SD SPI-mode driver Message-ID: <CAJ-Vmo=%2BtuHC4WA_5xPtjdJMGMn-_g6p5Nn7YjoPcuqb0s9AKg@mail.gmail.com> In-Reply-To: <1365609642.41399.237.camel@revolution.hippie.lan> References: <CAK1zEjs=hC%2BpAYBgGq4t7%2BA_JPLaH6rhvEjD%2B1RNk1Ziu8E-4g@mail.gmail.com> <CAD44qMWpz-sjNKwRH6K=xicFXYutfk7R%2BN%2B%2Bo7cbgTg7rcQbkA@mail.gmail.com> <CAK1zEjuVZU4A59q5GxLcKTnFF9mcrbVmJ=w268uSJ=3sxVf1PA@mail.gmail.com> <CAD44qMURrssyXUz-%2Btd226chPA_MbKJ29ZApozbT2cEYbQwSqw@mail.gmail.com> <CAJ-Vmo=nQMuuJAW786egjuXCf0LGOd9g%2BCEEKdOJjPLRQFpKUg@mail.gmail.com> <20130407011307.9a9a9d64.ray@freebsd.org> <CAJ-Vmo=aeLCmBYpn9YMsGjq%2B9aF_Es-rByJ3RSnYkJYUECtLuQ@mail.gmail.com> <20130407022428.86a66c6a.ray@freebsd.org> <CAJ-VmokXseALmvvA9wsgZEBKSP0AGA988592TbsRb%2B4F0-UEcw@mail.gmail.com> <20130408153334.9cc11688aedbf32dcbf83a7b@freebsd.org> <CAJ-Vmo=irADrYgM1Aw=fHbnO%2Bgf7kHy_xHeSY9mzTSifo34frg@mail.gmail.com> <1365605147.41399.227.camel@revolution.hippie.lan> <CAJ-Vmon3v1CV08u7dqn1w=Jwih2eCfjtJdmB_OjZU3cSzx-baA@mail.gmail.com> <1365609642.41399.237.camel@revolution.hippie.lan>
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On 10 April 2013 09:00, Ian Lepore <ian@freebsd.org> wrote: > I don't understand how reading is not a generic spi command > (presupposing the existance of the proposed changes that allow for a spi > read without a concurrent write and vice versa). No. Reading is an SPI method. But the SPI flash command for reading data is different than other SPI commands. The only thing we should be doing this for is SPI _flash reads_. Not SPI reads. Just data area reads from a directly attached flash chip. It's dirty or inefficient any way we do this. Either we special case spibus drivers, or we expose a SPI read / SPI write 'command' that knows it's not a generic SPI bus transaction but specifically a read-this-flash-data-from-this-offset-and-length transaction. Or some other kind of dirty hack. Adrian
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