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From: Mark Brown <broonie@kernel.org>
To: yuhang wang <wangyuhang2014@gmail.com>
Cc: "spi-devel-general@lists.sourceforge.net"
	<spi-devel-general@lists.sourceforge.net>,
	Sourav Poddar <sourav.poddar@ti.com>,
	Trent Piepho <tpiepho@gmail.com>,
	"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	"Gupta, Pekon" <pekon@ti.com>
Subject: Re: [PATCH V2] SPI: DUAL and QUAD support
Date: Mon, 29 Jul 2013 07:42:34 +0100	[thread overview]
Message-ID: <20130729064234.GS9858@sirena.org.uk> (raw)
In-Reply-To: <CAHSAbzNTUpsftZ1-fpv7UefuSdUvUidg9-SLOUXCTmSBhM0ZJQ@mail.gmail.com>


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On Mon, Jul 29, 2013 at 10:44:43AM +0800, yuhang wang wrote:

> > Your changes to spidev are not backward compatible at all.  You can
> > not change the data types in the ioctl and maintain backward
> > compatibility.  You can also not delete ioctls!

> well, please give me some details or specific situations. Why ioctl
> can not be changed. The operation that SPI_IOC_RD_LSB_FIRST do can be
> done in SPI_IOC_RD_MODE, so I dont think there is any necessary using
> SPI_IOC_RD_LSB_FIRST. What you worry about is the user already used
> SPI_IOC_RD_LSB_FIRST?

You need to make sure that existing userspace binaries can run
unmodified, changing the types will change the layout of the ioctl
arguments.  This may mean that you need to add new ioctls if you need to
change types.

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______________________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-mtd/

  reply	other threads:[~2013-07-29  6:42 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-27  9:39 [PATCH V2] SPI: DUAL and QUAD support wangyuhang
     [not found] ` <1374917973-7083-1-git-send-email-wangyuhang2014-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-07-29  0:32   ` Trent Piepho
     [not found]     ` <CA+7tXihU+JODQec-h2joUYiVY=otuSOu8BwADn+mtgELCFHPng-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-29  2:44       ` yuhang wang
2013-07-29  6:42         ` Mark Brown [this message]
     [not found]           ` <20130729064234.GS9858-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2013-07-29 10:53             ` [PATCH] " wangyuhang
2013-07-29 12:43               ` Gupta, Pekon
     [not found]                 ` <20980858CB6D3A4BAE95CA194937D5E73E9EE267-yXqyApvAXouIQmiDNMet8wC/G2K4zDHf@public.gmane.org>
2013-07-29 13:58                   ` yuhang wang
2013-07-29 14:21                     ` Gupta, Pekon
     [not found]                       ` <20980858CB6D3A4BAE95CA194937D5E73E9EE356-yXqyApvAXouIQmiDNMet8wC/G2K4zDHf@public.gmane.org>
2013-07-29 14:52                         ` yuhang wang
2013-07-29 23:26                         ` Trent Piepho
     [not found]                           ` <CA+7tXijduVqFdao3L3oJcFBYw_cffdyo-fwyAS2cBASfEMExpA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-30  7:30                             ` yuhang wang
2013-08-08  8:57                               ` Gupta, Pekon
     [not found]                                 ` <20980858CB6D3A4BAE95CA194937D5E73E9F1E1B-yXqyApvAXouIQmiDNMet8wC/G2K4zDHf@public.gmane.org>
2013-08-09  3:22                                   ` yuhang wang
2013-08-09  4:25                                     ` Gupta, Pekon
     [not found]                                       ` <20980858CB6D3A4BAE95CA194937D5E73E9F22F0-yXqyApvAXouIQmiDNMet8wC/G2K4zDHf@public.gmane.org>
2013-08-09  9:14                                         ` yuhang wang
2013-08-07 11:57                   ` Gupta, Pekon
     [not found]                     ` <20980858CB6D3A4BAE95CA194937D5E73E9F1993-yXqyApvAXouIQmiDNMet8wC/G2K4zDHf@public.gmane.org>
2013-08-09  2:09                       ` yuhang wang
2013-08-09  2:50                         ` Gupta, Pekon
     [not found]               ` <1375095194-7093-1-git-send-email-wangyuhang2014-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2013-07-29 12:56                 ` Matthieu CASTET
     [not found]                   ` <20130729145626.6c227aa0-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
2013-07-29 14:25                     ` yuhang wang
     [not found]                       ` <CAHSAbzOPfpbPHohG7-EzftiPr5T2m19qgrKg7KS2jSKD-B=goA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-29 15:35                         ` Matthieu CASTET
     [not found]                           ` <20130729173511.65caa07d-ITF29qwbsa/QT0dZR+AlfA@public.gmane.org>
2013-07-30  1:13                             ` yuhang wang

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