From mboxrd@z Thu Jan 1 00:00:00 1970 From: York Sun Date: Tue, 11 Feb 2014 10:01:40 -0800 Subject: [U-Boot] [PATCH] driver/mxc_i2c: Move static data structure to global_data In-Reply-To: <20140210224558.GF7049@bill-the-cat> References: <1392069772-24742-1-git-send-email-yorksun@freescale.com> <20140210221031.GD7049@bill-the-cat> <52F95271.6030006@freescale.com> <20140210224558.GF7049@bill-the-cat> Message-ID: <52FA6584.6070100@freescale.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 02/10/2014 02:45 PM, Tom Rini wrote: > On Mon, Feb 10, 2014 at 02:28:01PM -0800, York Sun wrote: >> On 02/10/2014 02:10 PM, Tom Rini wrote: >>> On Mon, Feb 10, 2014 at 02:02:52PM -0800, York Sun wrote: >>> >>>> This driver needs a data structure in SRAM before SDRAM is available. >>>> This is not alway the case using .data section. Moving this data >>>> structure to global_data guarantees it is writable. >>>> >>>> Signed-off-by: York Sun >>>> CC: Troy Kisky >>> >>> If you need something in SRAM then you need to place it in that section, >>> see arch/arm/cpu/armv7/am33xx/u-boot-spl.lds for example >>> >> >> I am not sure if it is a similar situation. But anyway, I am open to >> suggestions. >> >> For this driver, the variable needs to be writable. I guess it wasn't >> a problem for existing platforms which probably call this driver after >> relocation. >> >> Does the SRAM code/data relocate to SDRAM? I don't want this variable >> to stay in SRAM once u-boot relocates to normal memory. > > So in this case the problem is still within SPL right? You would put > the parts you need to have in SRAM during SPL and DDR in full U-Boot > with __attribute__((section(".data.srdata"))) and in the SoC's linker > scripts make sure that drivers/i2c/built-in.o(.data.srdata) ends up in > the appropriate place for each case. > > I say all of this as I think we really want to avoid expanding on > gd->arch-> stuff if we can (which reminds me, your patch expands on main > gd not gd->arch so NAK on that either way). > I tried the linker script and made it work. But it is not what I want. I expect this variable relocates to DDR, but the offset is not right. I am not using SPL. This is full u-boot, which boots from flash, calls i2c driver, initializes DDR, then relocates. Putting this variable into stack might be the solution. Suggestions? York