On 3/1/19 3:40 AM, Marek Vasut wrote:
On 3/1/19 12:59 AM, Dinh Nguyen wrote:
Hi Marek,
On 2/19/19 4:01 AM, Simon Goldschmidt wrote:
On Tue, Feb 19, 2019 at 1:44 AM Marek Vasut marex@denx.de wrote:
Configure the PL310 tag and data latency registers, which slightly improves performance and aligns the behavior with Linux.
Signed-off-by: Marek Vasut marex@denx.de Cc: Dalon Westergreen dwesterg@gmail.com Cc: Dinh Nguyen dinguyen@kernel.org
arch/arm/mach-socfpga/misc.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/arch/arm/mach-socfpga/misc.c b/arch/arm/mach-socfpga/misc.c index 78fbe28724..1ea4e32c11 100644 --- a/arch/arm/mach-socfpga/misc.c +++ b/arch/arm/mach-socfpga/misc.c @@ -62,6 +62,9 @@ void v7_outer_cache_enable(void) /* Disable the L2 cache */ clrbits_le32(&pl310->pl310_ctrl, L2X0_CTRL_EN);
writel(0x111, &pl310->pl310_tag_latency_ctrl);writel(0x121, &pl310->pl310_data_latency_ctrl);Would it make sense to add defines as named constants for this? OTOH, in Linux, the values in the devicetree aren't really described, either, so:
I was thinking the same, so I'm working on a patch to get these values from the device tree.
So while I was doing that, I realized that this patch is wrong.
The patch should be like this:
writel(0x0, &pl310->pl310_tag_latency_ctrl); writel(0x010, &pl310->pl310_data_latency_ctrl);
The reason is for the latency values:
000 = 1 cycle of latency, there is no additional latency. 001 = 2 cycles of latency. 010 = 3 cycles of latency. 011 = 4 cycles of latency. 100 = 5 cycles of latency. 101 = 6 cycles of latency. 110 = 7 cycles of latency. 111 = 8 cycles of latency.
So from the values in the device tree, they should be n-1.
It looks like you've already sent the patch to Tom. I'll send a follow up patch to fix that when it lands.
Drat, thanks.
Better yet, pull the latency config into a function, so it can be used by other platforms. The prototype should take 7 parameters, address and latency in cycles, so that it shields the users from this n-1 stuff.
Agreed. I'm working on an RFC patch that creates a UBOOT_MISC driver to handle all of the pl310 settings. Hope to send it out sometime next week.
Dinh