Dear Liu Hui-R64343, > Hi, Marek, > > >-----Original Message----- > >From: Marek Vasut [mailto:ma...@denx.de] > >Sent: Wednesday, June 13, 2012 8:25 PM > >To: u-boot@lists.denx.de > >Cc: Liu Hui-R64343; Dirk Behme > >Subject: Re: [U-Boot] [PATCH] mx6: Avoid writing to read-only bits in > >imximage.cfg > > > >Dear Liu Hui-R64343, > > > >[...] > > > >> >> >> According to REV C manual, the register IOMUXC_IOMUXC_GPR4 has > >> >> >> bits > >> >> >> 4 and 5 read-only and the value is always set as zero. > >> >> >> So write '0' to these bits instead of writing '1'. > >> >> > > >> >> >Jason, Fabio: What do you think? You should be the datasheet > >> >> >'masters' ;) > >> >> > >> >> Yes, according to the RM, > >> >> 5 > >> >> Reserved > >> >> This read-only field is reserved and always has the value 0. > >> >> 4 > >> >> Reserved > >> >> This read-only field is reserved and always has the value 0. > >> >> > >> >> So, write 1 should have no effect. > >> > > >> >I really dislike how "write 1 should have no effect" sounds. Can you > >> >please check with HW people? > >> > >> Since this is read-only bit, if you write 1 to it, it will have no > >> effect. > > > >For how long do you work with hardware? Did it never occur to you that > >when you wrote 1 to an "reserved" bit, it either did something you didn't > >expect or you had to rework it later because the new CPU has that bit for > >something else? > > > >> Yes, to avoid the confusion, for example to do the read-back check, I > >> agree with not writing '1' to the read-only bit. > > > >Please, ask the hardware people about this. > > Yes, I will and back to you.
Thanks! btw. sorry, I didn't meant to offend you. Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
