Hi, Marek,
-----Original Message----- From: Marek Vasut [mailto:marex@denx.de] Sent: Wednesday, June 13, 2012 7:18 PM To: u-boot@lists.denx.de Cc: Liu Hui-R64343; Dirk Behme; Fabio Estevam Subject: Re: [U-Boot] [PATCH] mx6: Avoid writing to read-only bits in imximage.cfg
Dear Liu Hui-R64343,
-----Original Message----- From: Dirk Behme [mailto:dirk.behme@de.bosch.com] Sent: Tuesday, June 12, 2012 11:05 PM To: Fabio Estevam; Liu Hui-R64343 Cc: Vikram Narayanan; u-boot@lists.denx.de Subject: Re: [U-Boot] [PATCH] mx6: Avoid writing to read-only bits in imximage.cfg
On 12.06.2012 16:50, Vikram Narayanan wrote:
If in case this is valid according to the latest datasheet, ignore this patch.
-- 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.
Yes, to avoid the confusion, for example to do the read-back check, I agree with not writing '1' to the read-only bit.
[..]
Best regards, Marek Vasut