On 3/3/2021 10:14 PM, Stephen Boyd wrote:
Quoting Elliot Berman (2021-03-03 19:35:08)
On 2/23/2021 1:45 PM, Stephen Boyd wrote:
These scm calls are never used outside of legacy ARMv7 based platforms.
That's because PSCI, mandated on arm64, implements them for modern SoCs
via the PSCI spec. Let's move them to the legacy file and only compile
the legacy file into the kernel when CONFIG_ARM=y. Otherwise provide
stubs and fail the calls. This saves a little bit of space in an
arm64 allmodconfig >
$ ./scripts/bloat-o-meter vmlinux.before vmlinux.after
add/remove: 0/8 grow/shrink: 5/7 up/down: 509/-4405 (-3896)
Function old new delta
__qcom_scm_set_dload_mode.constprop 312 452 +140
qcom_scm_qsmmu500_wait_safe_toggle 288 416 +128
qcom_scm_io_writel 288 408 +120
qcom_scm_io_readl 376 492 +116
__param_str_download_mode 23 28 +5
__warned 4327 4326 -1
qcom_iommu_init 272 268 -4
e843419@0b3f_00010432_324 8 - -8
qcom_scm_call 228 208 -20
CSWTCH 5925 5877 -48
_sub_I_65535_1 163100 163040 -60
_sub_D_65535_0 163100 163040 -60
qcom_scm_wb 64 - -64
qcom_scm_lock 320 160 -160
qcom_scm_call_atomic 212 - -212
qcom_scm_cpu_power_down 308 - -308
scm_legacy_call_atomic 520 - -520
qcom_scm_set_warm_boot_addr 720 - -720
qcom_scm_set_cold_boot_addr 728 - -728
scm_legacy_call 1492 - -1492
Total: Before=66737642, After=66733746, chg -0.01%
Commit 9a434cee773a ("firmware: qcom_scm: Dynamically support SMCCC and
legacy conventions") didn't mention any motivating factors for keeping
the legacy code around on arm64 kernels, i.e. presumably that commit
wasn't trying to support these legacy APIs on arm64 kernels.
There are arm targets which support SMCCC convention and use some of
these removed functions. Can these functions be kept in qcom-scm.c and
wrapped with #if IS_ENABLED(CONFIG_ARM)?
It can be wrapped in qcom-scm.c, but why? It's all the same object file
so I'm lost why it matters. I suppose it would make it so the struct
doesn't have to be moved around and declared in the header? Any other
reason? I moved it to the legacy file so that it was very obvious that
the API wasn't to be used except for "legacy" platforms that don't use
PSCI.
There are "legacy" arm platforms that use the SMCCC (scm_smc_call) and
use the qcom_scm_set_{warm,cold}_boot_addr and qcom_scm_cpu_power_down
functions.
> + desc.args[0] = flags;
> + desc.args[1] = virt_to_phys(entry);
> +
> + return scm_legacy_call_atomic(NULL, &desc, NULL);
> +}
> +EXPORT_SYMBOL(qcom_scm_set_cold_boot_addr);
This should still be qcom_scm_call.
