[PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL

[PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL

[Jit Loon Lim]

From: Kah Jing Lee <kah.jing.lee@intel.com>

Dcache feature is not enabled in SPL and enable it will cause ISR
exception. Since the Dcache is not supported in SPL, new
CONFIG_SPL_SYS_DISABLE_DCACHE_OPS is added to Kconfig to disable Dcache
in SPL.

Signed-off-by: Kah Jing Lee <kah.jing.lee@intel.com>
---
 arch/arm/cpu/armv8/cache_v8.c | 20 +++++++++++---------
 common/spl/Kconfig            |  7 +++++++
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c
index cb1131a048..7f25d3a6ce 100644
--- a/arch/arm/cpu/armv8/cache_v8.c
+++ b/arch/arm/cpu/armv8/cache_v8.c
@@ -534,29 +534,31 @@ inline void flush_dcache_all(void)
 #endif
 }
 
-#ifndef CONFIG_SYS_DISABLE_DCACHE_OPS
-/*
- * Invalidates range in all levels of D-cache/unified cache
- */
+#if CONFIG_IS_ENABLED(SYS_DISABLE_DCACHE_OPS) || \
+	CONFIG_IS_ENABLED(SPL_SYS_DISABLE_DCACHE_OPS) && \
+	CONFIG_IS_ENABLED(SPL_BUILD)
 void invalidate_dcache_range(unsigned long start, unsigned long stop)
 {
-	__asm_invalidate_dcache_range(start, stop);
 }
 
-/*
- * Flush range(clean & invalidate) from all levels of D-cache/unified cache
- */
 void flush_dcache_range(unsigned long start, unsigned long stop)
 {
-	__asm_flush_dcache_range(start, stop);
 }
 #else
+/*
+ * Invalidates range in all levels of D-cache/unified cache
+ */
 void invalidate_dcache_range(unsigned long start, unsigned long stop)
 {
+	__asm_invalidate_dcache_range(start, stop);
 }
 
+/*
+ * Flush range(clean & invalidate) from all levels of D-cache/unified cache
+ */
 void flush_dcache_range(unsigned long start, unsigned long stop)
 {
+	__asm_flush_dcache_range(start, stop);
 }
 #endif /* CONFIG_SYS_DISABLE_DCACHE_OPS */
 
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index 2c042ad306..7e458503df 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -19,6 +19,13 @@ config SPL
 menu "SPL configuration options"
 	depends on SPL
 
+config SPL_SYS_DISABLE_DCACHE_OPS
+	bool "Do not enable dcache operation in SPL"
+	depends on SPL
+	help
+	  Do not enable data cache operation in SPL. This will turn off the
+	  Dcache support and have the empty dcache declaration.
+
 config SPL_FRAMEWORK
 	bool "Support SPL based upon the common SPL framework"
 	default y
-- 
2.26.2

Re: [PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL

[Marc Zyngier]

On Wed, 21 Jun 2023 15:06:51 +0100,
Jit Loon Lim <jit.loon.lim@intel.com> wrote:
> 
> From: Kah Jing Lee <kah.jing.lee@intel.com>
> 
> Dcache feature is not enabled in SPL and enable it will cause ISR
> exception. Since the Dcache is not supported in SPL, new
> CONFIG_SPL_SYS_DISABLE_DCACHE_OPS is added to Kconfig to disable Dcache
> in SPL.
> 
> Signed-off-by: Kah Jing Lee <kah.jing.lee@intel.com>

This is missing your own SoB.

Now, I'd like to understand what you are actually trying to fix. What
is this 'ISR' exception? This isn't something the architecture
describes. Unless you are using CMOs on something that isn't memory or
for which you don't have a mapping, this should never generate an
exception.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.

Re: [PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL

[Marek Vasut]

On 6/21/23 16:06, Jit Loon Lim wrote:
> From: Kah Jing Lee <kah.jing.lee@intel.com>
> 
> Dcache feature is not enabled in SPL and enable it will cause ISR
> exception

Why would it cause an exception ?

Re: [PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL

[Marek Vasut]

On 6/21/23 16:15, Marc Zyngier wrote:
> On Wed, 21 Jun 2023 15:06:51 +0100,
> Jit Loon Lim <jit.loon.lim@intel.com> wrote:
>>
>> From: Kah Jing Lee <kah.jing.lee@intel.com>
>>
>> Dcache feature is not enabled in SPL and enable it will cause ISR
>> exception. Since the Dcache is not supported in SPL, new
>> CONFIG_SPL_SYS_DISABLE_DCACHE_OPS is added to Kconfig to disable Dcache
>> in SPL.
>>
>> Signed-off-by: Kah Jing Lee <kah.jing.lee@intel.com>
> 
> This is missing your own SoB.
> 
> Now, I'd like to understand what you are actually trying to fix. What
> is this 'ISR' exception? This isn't something the architecture
> describes. Unless you are using CMOs on something that isn't memory or
> for which you don't have a mapping, this should never generate an
> exception.

You beat me to it, indeed, thanks !

RE: [PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL

[Lim, Jit Loon]

> -----Original Message-----
> From: Marek Vasut <marex@denx.de>
> Sent: Wednesday, 21 June, 2023 10:20 PM
> To: Marc Zyngier <maz@kernel.org>; Lim, Jit Loon <jit.loon.lim@intel.com>
> Cc: u-boot@lists.denx.de; Jagan Teki <jagan@amarulasolutions.com>; Simon
> <simon.k.r.goldschmidt@gmail.com>; Chee, Tien Fong
> <tien.fong.chee@intel.com>; Hea, Kok Kiang <kok.kiang.hea@intel.com>;
> Lokanathan, Raaj <raaj.lokanathan@intel.com>; Maniyam, Dinesh
> <dinesh.maniyam@intel.com>; Ng, Boon Khai <boon.khai.ng@intel.com>;
> Yuslaimi, Alif Zakuan <alif.zakuan.yuslaimi@intel.com>; Chong, Teik Heng
> <teik.heng.chong@intel.com>; Zamri, Muhammad Hazim Izzat
> <muhammad.hazim.izzat.zamri@intel.com>; Tang, Sieu Mun
> <sieu.mun.tang@intel.com>; Ying-Chun Liu <paul.liu@linaro.org>; Lee, Kah
> Jing <kah.jing.lee@intel.com>
> Subject: Re: [PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL
> 
> On 6/21/23 16:15, Marc Zyngier wrote:
> > On Wed, 21 Jun 2023 15:06:51 +0100,
> > Jit Loon Lim <jit.loon.lim@intel.com> wrote:
> >>
> >> From: Kah Jing Lee <kah.jing.lee@intel.com>
> >>
> >> Dcache feature is not enabled in SPL and enable it will cause ISR
> >> exception. Since the Dcache is not supported in SPL, new
> >> CONFIG_SPL_SYS_DISABLE_DCACHE_OPS is added to Kconfig to disable
> >> Dcache in SPL.
> >>
> >> Signed-off-by: Kah Jing Lee <kah.jing.lee@intel.com>
> >
> > This is missing your own SoB.
> >
> > Now, I'd like to understand what you are actually trying to fix. What
> > is this 'ISR' exception? This isn't something the architecture
> > describes. Unless you are using CMOs on something that isn't memory or
> > for which you don't have a mapping, this should never generate an
> > exception.
> 
> You beat me to it, indeed, thanks !

The intention of doing this is because when we init SDMMC driver, the driver will call the invalidate_dcache_range. 
However, during that time, the dcache is not available in SPL yet thus causing exception. 
https://elixir.bootlin.com/u-boot/latest/source/drivers/mmc/sdhci.c#L181 -> https://elixir.bootlin.com/u-boot/latest/source/include/linux/dma-mapping.h#L55 -> https://elixir.bootlin.com/u-boot/latest/source/arch/arm/cpu/armv8/cache_v8.c#L475

Re: [PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL

[Marc Zyngier]

On Mon, 26 Jun 2023 10:00:09 +0100,
"Lim, Jit Loon" <jit.loon.lim@intel.com> wrote:
> 
> 
> 
> > -----Original Message-----
> > From: Marek Vasut <marex@denx.de>
> > Sent: Wednesday, 21 June, 2023 10:20 PM
> > To: Marc Zyngier <maz@kernel.org>; Lim, Jit Loon <jit.loon.lim@intel.com>
> > Cc: u-boot@lists.denx.de; Jagan Teki <jagan@amarulasolutions.com>; Simon
> > <simon.k.r.goldschmidt@gmail.com>; Chee, Tien Fong
> > <tien.fong.chee@intel.com>; Hea, Kok Kiang <kok.kiang.hea@intel.com>;
> > Lokanathan, Raaj <raaj.lokanathan@intel.com>; Maniyam, Dinesh
> > <dinesh.maniyam@intel.com>; Ng, Boon Khai <boon.khai.ng@intel.com>;
> > Yuslaimi, Alif Zakuan <alif.zakuan.yuslaimi@intel.com>; Chong, Teik Heng
> > <teik.heng.chong@intel.com>; Zamri, Muhammad Hazim Izzat
> > <muhammad.hazim.izzat.zamri@intel.com>; Tang, Sieu Mun
> > <sieu.mun.tang@intel.com>; Ying-Chun Liu <paul.liu@linaro.org>; Lee, Kah
> > Jing <kah.jing.lee@intel.com>
> > Subject: Re: [PATCH v1] cache_v8: agilex5: Disable Dcache in the SPL
> > 
> > On 6/21/23 16:15, Marc Zyngier wrote:
> > > On Wed, 21 Jun 2023 15:06:51 +0100,
> > > Jit Loon Lim <jit.loon.lim@intel.com> wrote:
> > >>
> > >> From: Kah Jing Lee <kah.jing.lee@intel.com>
> > >>
> > >> Dcache feature is not enabled in SPL and enable it will cause ISR
> > >> exception. Since the Dcache is not supported in SPL, new
> > >> CONFIG_SPL_SYS_DISABLE_DCACHE_OPS is added to Kconfig to disable
> > >> Dcache in SPL.
> > >>
> > >> Signed-off-by: Kah Jing Lee <kah.jing.lee@intel.com>
> > >
> > > This is missing your own SoB.
> > >
> > > Now, I'd like to understand what you are actually trying to fix. What
> > > is this 'ISR' exception? This isn't something the architecture
> > > describes. Unless you are using CMOs on something that isn't memory or
> > > for which you don't have a mapping, this should never generate an
> > > exception.
> > 
> > You beat me to it, indeed, thanks !
> 
> The intention of doing this is because when we init SDMMC driver,
> the driver will call the invalidate_dcache_range.  However, during
> that time, the dcache is not available in SPL yet thus causing
> exception.

Again: which exception?

There is no such thing as "the dcache isn't available". It is always
valid to invalidate it, irrespective of it being enabled or not.

My impression is that you are papering over another bug (such as
feeding non-memory to the CMOs), and are getting an SError back, which
would be entirely justified.

	M.

-- 
Without deviation from the norm, progress is not possible.