Wolfgang, Yes, that is not just word-aligned, instead, the Dm6467 UART access need to be "Word LOAD/STORE". Thus, if I use STRB <THR> instead of STR <THR> to transmit a character, it doesn't work.
As you said, using prepad/postpad, we can define the alignment but my understanding is that the final register access will be byte access only as the register will be declared as "unsigned char". For generating 32-bit load/store, probably we need to declare register members as "unsigned long". Or can we achieve the same without any code changes? Thanks - Hemant > -----Original Message----- > From: Wolfgang Denk [mailto:w...@denx.de] > Sent: Tuesday, January 05, 2010 1:05 PM > To: Pedanekar, Hemant > Cc: u-boot@lists.denx.de; d...@denx.de > Subject: Re: [U-Boot] NS16550 Register structure > > Dear "Pedanekar, Hemant", > > In message <2a3dcf3da181ad40bde86a3150b27b6b03094b2...@dbde02.ent.ti.com> > you wrote: > > > > I have observed that in the recent commit (file include/ns16550.h), the > ns16550 UART register structure declaration is changed so that > irrespective of the CONFIG_SYS_NS16550_REG_SIZE setting the register > access will be done at byte level. > > This seems to be working on all systems so far, which is not so much > of a surprise as the registers are 8 bit wide only. > > > This crates problem when UART space access is required to be word- > aligned. I am particularly referring to DaVinci DM6467, where STRB over > UART register space is not supported and requires 32-bit access (L/STR). > > Please make sure to use exact terms. Alignment is one thing, and bus > width is another one. Alignment can be easily adjusted using the > prepad_* or postpad_* settings. > > > If I go ahead and add a specific handling in ns16550.h file (structure > register members as "long"), I would end up making code similar to the one > earlier to last commit. Is there a better way to handle such case? > > No such changes should be needed, as far as I understand the code. > > Best regards, > > Wolfgang Denk > > -- > DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany > Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de > In theory, there is no difference between theory and practice. In > practice, however, there is. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
