Messages in this thread | | | From | Doug Anderson <> | Date | Wed, 11 Mar 2020 08:27:44 -0700 | Subject | Re: [RFT PATCH 2/9] drivers: qcom: rpmh-rsc: Document the register layout better |
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Hi,
On Wed, Mar 11, 2020 at 2:35 AM Maulik Shah <mkshah@codeaurora.org> wrote: > > Hi Doug, > > On 3/7/2020 5:29 AM, Douglas Anderson wrote: > > Perhaps it's just me, it took a really long time to understand what > > the register layout of rpmh-rsc was just from the #defines. > i don't understand why register layout is so important for you to understand? > > besides, i think all required registers are properly named with #define > > for e.g. > /* Register offsets */ > #define RSC_DRV_IRQ_ENABLE 0x00 > #define RSC_DRV_IRQ_STATUS 0x04 > #define RSC_DRV_IRQ_CLEAR 0x08 > > now when you want to enable/disable irq in driver code, its pretty simple to figure out > that we need to read/write at RSC_DRV_IRQ_ENABLE offset.
It's not the specific layout that's important to me. It's the relationships between everything. In other words:
a) one rpmh-rsc contains some registers and then a whole bunch of TCS blocks
b) one TCS block contains some registers and space for up to 16 commands.
c) each command has a handful of registers
Nothing describes this in the existing code--you've gotta read through all the code and figure out how it's reading/writing registers to figure it out.
> this seems unnecessary change to me, can you please drop this when you spin v2?
In v2 I'll replace this with the prose below. Personally I find this inferior to the struct definitions which are easier to read at-a-glance, but it seems like it would be less controversial...
/* * Here's a high level overview of how all the registers in RPMH work * together: * * - The main rpmh-rsc address is the base of a register space that can * be used to find overall configuration of the hardware * (DRV_PRNT_CHLD_CONFIG). Also found within the rpmh-rsc register * space are all the TCS blocks. The offset of the TCS blocks is * specified in the device tree by "qcom,tcs-offset" and used to * compute tcs_base. * - TCS blocks come one after another. Type, count, and order are * specified by the device tree as "qcom,tcs-config". * - Each TCS block has some registers, then space for up to 16 commands. * Note that though address space is reserved for 16 commands, fewer * might be present. See ncpt (num cmds per TCS). * - The first TCS block is special in that it has registers to control * interrupts (RSC_DRV_IRQ_XXX). Space for these registers is reserved * in all TCS blocks to make the math easier, but only the first one * matters. */
I'll also move the documentation of "irq_clear", "cmd_wait_for_cmpl", "status", and "cmd_enable" next to the respective #defines.
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