Re: [PATCH] remoteproc: qcom_q6v5_mss: Don't require PAS for memory protection

On 26-08-21 01:15:40, Paul Hollinsky wrote:
> Commit f3b1357673dd ("remoteproc: qcom_q6v5_mss: Switch to generic PAS
> TZ APIs") changed the probe-time gate for need_mem_protection platforms
> from qcom_scm_is_available() to qcom_pas_is_available(). Memory
> protection in this driver is implemented with qcom_scm_assign_mem(),
> which is a TZ service distinct from PAS. The only PAS call in the driver
> is qcom_pas_mem_setup(), and it is already guarded by need_pas_mem_setup.
> 
> No descriptor sets both flags: sc7180, sc7280, sdm660, sdm845, msm8996
> and msm8998 set need_mem_protection only, while msm8937, msm8940 and
> msm8953 set need_pas_mem_setup only. On TrustZone firmware that does not
> implement PAS - for example SC7180 Chromebooks, where call-availability
> queries report every QCOM_SCM_SVC_PIL command as unavailable - the modem
> consequently never probes:
> 
>   platform 4080000.remoteproc: deferred probe pending: (reason unknown)
> 
> On those machines the modem is also what loads the WLAN firmware, so
> ath10k never receives QMI and wifi does not come up either.
> 
> Gate memory protection on SCM availability as it was before, and require
> PAS only where a PAS call is actually issued. Keeping the SCM check
> matters: qcom_scm_assign_mem() passes __scm->mempool to
> qcom_tzmem_alloc() without testing __scm, so dropping the gate entirely
> would allow a NULL dereference when qcom_scm has not yet probed.
> 
> Fixes: f3b1357673dd ("remoteproc: qcom_q6v5_mss: Switch to generic PAS TZ APIs")
> Link: https://lore.kernel.org/r/[email protected]
> Signed-off-by: Paul Hollinsky <[email protected]>

Reviewed-by: Abel Vesa <[email protected]>