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. > >> >[..] >> > >> >Best regards, >> >Marek Vasut > >Best regards, >Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
