From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ned Forrester Subject: Re: [PATCH] pxa2xx_spi: wait_rx_stall before deasserting CS on PIO mode Date: Thu, 11 Sep 2008 22:59:42 -0400 Message-ID: <48C9DB1E.2060107@whoi.edu> References: <6669365c0808171553i3f64b667t18fcea589d94411a@mail.gmail.com> <48A9C515.3000908@whoi.edu> <6669365c0808181227k2fa01d6fu570cebc10630f55d@mail.gmail.com> <200809111041.20900.david-b@pacbell.net> <1221184432.5078.19.camel@brutus> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: David Brownell , spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Daniel Ribeiro Return-path: In-Reply-To: <1221184432.5078.19.camel@brutus> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org Ned Forrester wrote: > Daniel Ribeiro wrote: > In a past message, you showed the automatic declarations that went with > the above code: > > > struct spi_transfer t; > > struct spi_message m; > > While spi_message_init() zeros the memory in "m", you don't show any > code above, other than your assignments, that clears the memory in "t". > Thus, if you omit the assignments for t.delay_usecs or t.speed_hz (or > any other member of t), then you are passing uninitialized memory. You > could use memset to clear t, or dynamically allocate zeroed memory. > > Normally, you use the per-transfer values: > > t.bits_per_word > t.speed_hz > > only when you need to make them different from the default values set > when you previously called spi_setup() I forgot to mention that if either of these values is zero, then the default parameters set by initialization or spi_setup are used. If either value is non-zero, then the defaults are overridden. In your case, the uninitialized memory overrode the defaults. -- Ned Forrester nforrester-/d+BM93fTQY@public.gmane.org Oceanographic Systems Lab 508-289-2226 Applied Ocean Physics and Engineering Dept. Woods Hole Oceanographic Institution Woods Hole, MA 02543, USA http://www.whoi.edu/sbl/liteSite.do?litesiteid=7212 http://www.whoi.edu/hpb/Site.do?id=1532 ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/