Messages in this thread | | | Date | Mon, 17 Dec 2012 14:32:33 +0100 | From | Roland Stigge <> | Subject | Re: [PATCH RESEND 0/6 v10] gpio: Add block GPIO |
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On 12/17/2012 12:51 PM, Wolfgang Grandegger wrote: >>> Without having an AT91 available right now, I guess the hardware >>> interface of this GPIO chip is different from the GPIO block API. While >>> the hardware has clear and set registers, the val parameter of >>> at91_gpiolib_set_block() should be interpreted as the actual output >>> values. See lpc32xx_gpo_set_block() for an example for handling set and >>> clear registers like this: First, set_bits and clear_bits words are >>> calculated from mask and val parameters, and finally written to the >>> respective hardware registers. >>> >>> Note that one .set_block() can result in writing both the set and clear >>> registers of the hardware when val contains both 0s and 1s in >>> respectively masked positions. >> >> Oops, I obviously did not test GPIO block write. The patch below does >> work now. Feel free to add it to the next version of your series. > > The patch lacks an important fix, sorry. Please consider the updated > patch below.
Thanks!
And I guess Russell is right: If possible, we should write outputs simultaneously via ODSR (plus OWER/OWDR/OWSR) instead of separate set/clear.
I wonder if we need to save/restore the state of OWSR at every write operation or if we need/can cache it. Assuming that block GPIO are the only code in the kernel that manipulates ODSR.
Further: Can we include this patch for arch/arm/mach-at91 via the gpio subsystem or does it need to go separately via arm-soc.git?
Thanks,
Roland
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