[PATCH v3] remoteproc: mediatek: fix side effect of mt8195 sram power on

[Tinghan Shen]

Hi Angelo,

On Mon, 2022-03-14 at 12:31 +0100, AngeloGioacchino Del Regno wrote:
> Il 14/03/22 12:18, Tinghan Shen ha scritto:
> > The definition of L1TCM_SRAM_PDN bits on mt8195 is different to mt8192.
> > 
> > L1TCM_SRAM_PDN bits[3:0] control the power of mt8195 L1TCM SRAM.
> > 
> > L1TCM_SRAM_PDN bits[7:4] control the access path to EMI for SCP.
> > These bits have to be powered on to allow EMI access for SCP.
> > 
> > Bits[7:4] also affect audio DSP because audio DSP and SCP are
> > placed on the same hardware bus. If SCP cannot access EMI, audio DSP is
> > blocked too.
> > 
> > L1TCM_SRAM_PDN bits[31:8] are not used.
> > 
> > This fix removes modification of bits[7:4] when power on/off mt8195 SCP
> > L1TCM. It's because the modification introduces a short period of time
> > blocking audio DSP to access EMI. This was not a problem until we have
> > to load both SCP module and audio DSP module. audio DSP needs to access
> > EMI because it has source/data on DRAM. Audio DSP will have unexpected
> > behavior when it accesses EMI and the SCP driver blocks the EMI path at
> > the same time.
> > 
> > Signed-off-by: Tinghan Shen <tinghan.shen at mediatek.com>
> 
> 
> Hello Tinghan,
> 
> I'm sorry, but in the last review I forgot to mention that you should
> really add a Fixes tag to this commit, since this is.. a fix.
> 
> This is the tag that you should use:
> 
> Fixes: 79111df414fc ("remoteproc: mediatek: Support mt8195 scp")
> 
> After adding that,
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>
> 

I'll add it at next version.
thank you very much!

Best regards,
TingHan

> > ---
> > v3: fix build error
> > v2: apply comments about macro definition and function calls
> > ---
> >   drivers/remoteproc/mtk_common.h |  2 +
> >   drivers/remoteproc/mtk_scp.c    | 67 +++++++++++++++++++++++++--------
> >   2 files changed, 53 insertions(+), 16 deletions(-)
> >