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

[Tinghan Shen]

Hi Angelo,

I'll update your suggestions at next version.
Thank you.


Best regards,
Tinghan

On Thu, 2022-03-10 at 15:40 +0100, AngeloGioacchino Del Regno wrote:
> Il 09/03/22 12:47, 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>
> > ---
> >   drivers/remoteproc/mtk_common.h |  4 +++
> >   drivers/remoteproc/mtk_scp.c    | 57 +++++++++++++++++++++++++++++----
> >   2 files changed, 55 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/remoteproc/mtk_common.h b/drivers/remoteproc/mtk_common.h
> > index 5ff3867c72f3..27e7172c926d 100644
> > --- a/drivers/remoteproc/mtk_common.h
> > +++ b/drivers/remoteproc/mtk_common.h
> > @@ -51,6 +51,10 @@
> >   #define MT8192_CORE0_WDT_IRQ		0x10030
> >   #define MT8192_CORE0_WDT_CFG		0x10034
> >   
> > +#define MT8195_L1TCM_SRAM_PDN_RESERVED_RSI_BITS		0xF0
> 
> This is GENMASK(7, 4)..
> 
> > +#define MT8195_L1TCM_SRAM_PDN_RESERVED_BITS \
> > +	MT8195_L1TCM_SRAM_PDN_RESERVED_RSI_BITS
> > +
> 
> Why are you defining the same thing twice?
> Please drop this.
> 
> >   #define SCP_FW_VER_LEN			32
> >   #define SCP_SHARE_BUFFER_SIZE		288
> >   
> > diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c
> > index dcddb33e9997..4d75af856fd1 100644
> > --- a/drivers/remoteproc/mtk_scp.c
> > +++ b/drivers/remoteproc/mtk_scp.c
> > @@ -365,22 +365,32 @@ static int mt8183_scp_before_load(struct mtk_scp *scp)
> >   	return 0;
> >   }
> >   
> > -static void mt8192_power_on_sram(void __iomem *addr)
> > +static void scp_sram_power_on(void __iomem *addr, u32 reserved_mask)
> >   {
> >   	int i;
> >   
> >   	for (i = 31; i >= 0; i--)
> > -		writel(GENMASK(i, 0), addr);
> > +		writel(GENMASK(i, 0) & ~reserved_mask, addr);
> >   	writel(0, addr);
> >   }
> >   
> > -static void mt8192_power_off_sram(void __iomem *addr)
> > +static void scp_sram_power_off(void __iomem *addr, u32 reserved_mask)
> >   {
> >   	int i;
> >   
> >   	writel(0, addr);
> >   	for (i = 0; i < 32; i++)
> > -		writel(GENMASK(i, 0), addr);
> > +		writel(GENMASK(i, 0) & ~reserved_mask, addr);
> > +}
> > +
> > +static void mt8192_power_on_sram(void __iomem *addr)
> > +{
> > +	scp_sram_power_on(addr, 0);
> > +}
> > +
> > +static void mt8192_power_off_sram(void __iomem *addr)
> > +{
> > +	scp_sram_power_off(addr, 0);
> >   }
> >   
> >   static int mt8192_scp_before_load(struct mtk_scp *scp)
> > @@ -403,6 +413,27 @@ static int mt8192_scp_before_load(struct mtk_scp *scp)
> >   	return 0;
> >   }
> >   
> > +static int mt8195_scp_before_load(struct mtk_scp *scp)
> > +{
> > +	/* clear SPM interrupt, SCP2SPM_IPC_CLR */
> > +	writel(0xff, scp->reg_base + MT8192_SCP2SPM_IPC_CLR);
> > +
> > +	writel(1, scp->reg_base + MT8192_CORE0_SW_RSTN_SET);
> > +
> > +	/* enable SRAM clock */
> > +	mt8192_power_on_sram(scp->reg_base + MT8192_L2TCM_SRAM_PD_0);
> 
> At this point, you can simply use scp_sram_power_{on, off} instead of defining
> a new function for just one call... I get that your intent here is to enhance
> human readability, but I don't think that this is really happening with that and,
> if it is, it's just about a little ignorable difference.
> 
> Please use scp_sram_power_on() and scp_sram_power_off() directly.
> 
> 	scp_sram_power_on(scp->reg_base + MT8192_L2TCM_SRAM_PD_1, 0);
> 	... etc :)
> 
> > +	mt8192_power_on_sram(scp->reg_base + MT8192_L2TCM_SRAM_PD_1);
> > +	mt8192_power_on_sram(scp->reg_base + MT8192_L2TCM_SRAM_PD_2);
> > +	scp_sram_power_on(scp->reg_base + MT8192_L1TCM_SRAM_PDN,
> > +			  MT8195_L1TCM_SRAM_PDN_RESERVED_BITS);
> > +	mt8192_power_on_sram(scp->reg_base + MT8192_CPU0_SRAM_PD);
> > +
> > +	/* enable MPU for all memory regions */
> > +	writel(0xff, scp->reg_base + MT8192_CORE0_MEM_ATT_PREDEF);
> > +
> > +	return 0;
> > +}
> > +
> 
> Please remember to add me to the Cc's for the next version, so that I will be
> able to timely give you my R-b tag for this one.
> 
> Regards,
> Angelo
> 
>