Messages in this thread | | | Subject | Re: [PATCH 01/16] remoteproc: Extend rproc_da_to_va() API with a flags parameter | From | David Lechner <> | Date | Thu, 29 Nov 2018 10:12:42 -0600 |
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On 11/29/18 4:29 AM, Roger Quadros wrote: > Bjorn, Suman, > > On 26/11/18 23:29, David Lechner wrote: >> On 11/26/18 1:52 AM, Roger Quadros wrote: >>> From: Suman Anna <s-anna@ti.com> >>> >>> The rproc_da_to_va() API is currently used to perform any device >>> to kernel address translations to meet the different needs of the >>> remoteproc core/platform drivers (eg: loading). The function also >>> invokes the da_to_va ops, if present, to allow the remoteproc >>> platform drivers to provide address translation. However, not all >>> platform implementations have linear address spaces, and may need >>> an additional parameter to be able to perform proper translations. >>> >>> The rproc_da_to_va() API and the rproc .da_to_va ops have therefore >>> been expanded to take in an additional flags field enabling some >>> remoteproc implementations (like the TI PRUSS remoteproc driver) >>> to use these flags. Also, define some semantics for this flags >>> argument as this can vary from one implementation to another. A >>> new flags type is encoded into the upper 16 bits along side the >>> actual value in the lower 16-bits for the flags argument, to >>> allow different individual implementations to have better >>> flexibility in interpreting the flags as per their needs. >> >> This seems like an overly complex solution for a rather simple >> problem. Instead of passing all sorts of flags, could we just add >> a parameter named "page" to da_to_va() that indicates the memory >> page of the address in the remote processor? >> >> Or perhaps there is some other use for all of these flags that I >> am not aware of? > > I'm not a big fan of this patch either. > > rproc_da_to_va() is used at the following places > > 2 qcom_q6v5_mss.c qcom_q6v5_dump_segment 974 void *ptr = rproc_da_to_va(rproc, segment->da, segment->size, > 3 remoteproc_core.c rproc_da_to_va 197 void *rproc_da_to_va(struct rproc *rproc, u64 da, int len, u32 flags) > 4 remoteproc_core.c rproc_handle_trace 582 ptr = rproc_da_to_va(rproc, rsc->da, rsc->len, RPROC_FLAGS_NONE); > 5 remoteproc_core.c rproc_coredump 1592 ptr = rproc_da_to_va(rproc, segment->da, segment->size, > 6 remoteproc_elf_loader.c rproc_elf_load_segments 185 ptr = rproc_da_to_va(rproc, da, memsz, > 7 remoteproc_elf_loader.c rproc_elf_find_loaded_rsc_table 337 return rproc_da_to_va(rproc, shdr->sh_addr, shdr->sh_size, > > At rproc_elf_load_segments() we need to pass enough information so that > the rproc driver can load the segment into proper area (IRAM vs DRAM). > So providing page should suffice.
FYI, the PRU series I sent a while back has some patches to do something like this so feel free to use them if they are helpful.
https://lore.kernel.org/lkml/20180623210810.21232-2-david@lechnology.com/ https://lore.kernel.org/lkml/20180623210810.21232-3-david@lechnology.com/
> > I want to understand more about rproc_elf_find_loaded_rsc_table() myself. > rproc_elf_find_loaded_rsc_table() is called only in rproc_start() in remoteproc_core.c > with the comment > > /* > * The starting device has been given the rproc->cached_table as the > * resource table. The address of the vring along with the other > * allocated resources (carveouts etc) is stored in cached_table. > * In order to pass this information to the remote device we must copy > * this information to device memory. We also update the table_ptr so > * that any subsequent changes will be applied to the loaded version. > */ > loaded_table = rproc_find_loaded_rsc_table(rproc, fw); > > Why isn't cached_table sufficient? > Why do we need to call rproc_find_loaded_rsc_table()? > > why do we need to load the resource table into remote processor memory at all. > As discussed earlier, some PRU systems have very little memory (512 bytes?) > and we want to avoid unnecessary loading. > > cheers, > -roger >
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