[PATCH v3] ACPI / tables: Add IORT to injectable table list

[PATCH v3] ACPI / tables: Add IORT to injectable table list

[Yang Shunyong]

Loading IORT table from initrd is used to fix firmware IORT defects.
Moreover, it is very useful to debug SMMU node/device probe, MSI
allocation, stream id translation and IORT table from firmware. It
is also very useful to enable SMMU and devices behind SMMU before
firmware is ready.

This patch adds ACPI_SIG_IORT to the table, which enables IORT
from initrd to override which from firmware.

Signed-off-by: Yang Shunyong <shunyong.yang@hxt-semitech.com>
Cc: Joey Zheng <yu.zheng@hxt-semitech.com>
Cc: Wang Dongsheng <dongsheng.wang@hxt-semitech.com>
Cc: Jiang Yutang <yutang2.jiang@hxt-semitech.com>
Cc: Hanjun Guo <guohanjun@huawei.com>
---

v3:
Add more detailed commit message according to Hanjun's suggestion.

v2:
Change typo ACPI_SIG_PPTT to ACPI_SIG_IORT in commit message.

---
 drivers/acpi/tables.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 80ce2a7d224b..7bcb66ccccf3 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -456,7 +456,8 @@ static u8 __init acpi_table_checksum(u8 *buffer, u32 length)
 	ACPI_SIG_SLIC, ACPI_SIG_SPCR, ACPI_SIG_SPMI, ACPI_SIG_TCPA,
 	ACPI_SIG_UEFI, ACPI_SIG_WAET, ACPI_SIG_WDAT, ACPI_SIG_WDDT,
 	ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT, ACPI_SIG_PSDT,
-	ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, NULL };
+	ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT, ACPI_SIG_IORT,
+	NULL };
 
 #define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)
 
-- 
1.8.3.1

Re: [PATCH v3] ACPI / tables: Add IORT to injectable table list

[Hanjun Guo]

On 2018/2/2 18:25, Yang Shunyong wrote:
> Loading IORT table from initrd is used to fix firmware IORT defects.

I don't think this fix "firmware defects", it just for debug purpose,
we will not use that for production purpose, right? I think above line
can be removed.

> Moreover, it is very useful to debug SMMU node/device probe, MSI
> allocation, stream id translation and IORT table from firmware. It
> is also very useful to enable SMMU and devices behind SMMU before
> firmware is ready.
> 
> This patch adds ACPI_SIG_IORT to the table, which enables IORT
> from initrd to override which from firmware.
> 
> Signed-off-by: Yang Shunyong <shunyong.yang@hxt-semitech.com>
> Cc: Joey Zheng <yu.zheng@hxt-semitech.com>
> Cc: Wang Dongsheng <dongsheng.wang@hxt-semitech.com>
> Cc: Jiang Yutang <yutang2.jiang@hxt-semitech.com>
> Cc: Hanjun Guo <guohanjun@huawei.com>

With that updated,

Acked-by: Hanjun Guo <hanjun.guo@linaro.org>

Thanks
Hanjun

Re: Re: [PATCH v3] ACPI / tables: Add IORT to injectable table list

[Wang, Dongsheng]

Hey, Hanjun,

On 2018/2/2 19:54:24, "Hanjun Guo" <guohanjun@huawei.com> wrote:

>On 2018/2/2 18:25, Yang Shunyong wrote:
>>Loading IORT table from initrd is used to fix firmware IORT defects.
>
>I don't think this fix "firmware defects", it just for debug purpose,
>we will not use that for production purpose, right? I think above line
>can be removed.
>
I thinks the upgrade feature not only for debug. Here's an important
way to fix bugs that come from the firmware.

Documentation/acpi/initrd_table_override.txt


Cheers,
-Dongsheng

Re: [PATCH v3] ACPI / tables: Add IORT to injectable table list

[Jon Masters]

On 02/02/2018 07:12 AM, Wang, Dongsheng wrote:
> Hey, Hanjun,
> 
> On 2018/2/2 19:54:24, "Hanjun Guo" <guohanjun@huawei.com> wrote:
> 
>> On 2018/2/2 18:25, Yang Shunyong wrote:
>>> Loading IORT table from initrd is used to fix firmware IORT defects.
>>
>> I don't think this fix "firmware defects", it just for debug purpose,
>> we will not use that for production purpose, right? I think above line
>> can be removed.
>>
> I thinks the upgrade feature not only for debug. Here's an important
> way to fix bugs that come from the firmware.
> 
> Documentation/acpi/initrd_table_override.txt

I think we should message that this is for debug/development use.
Ultimately, it's not the way to address firmware problems. Firmware
needs to address that by shipping the correct(ed) tables :)

-- 
Computer Architect

Re: [PATCH v3] ACPI / tables: Add IORT to injectable table list

[Yang, Shunyong]

Hi, Jon,

On Mon, 2018-02-19 at 14:13 -0500, Jon Masters wrote:
> On 02/02/2018 07:12 AM, Wang, Dongsheng wrote:
> > 
> > Hey, Hanjun,
> > 
> > On 2018/2/2 19:54:24, "Hanjun Guo" <guohanjun@huawei.com> wrote:
> > 
> > > 
> > > On 2018/2/2 18:25, Yang Shunyong wrote:
> > > > 
> > > > Loading IORT table from initrd is used to fix firmware IORT
> > > > defects.
> > > I don't think this fix "firmware defects", it just for debug
> > > purpose,
> > > we will not use that for production purpose, right? I think above
> > > line
> > > can be removed.
> > > 
> > I thinks the upgrade feature not only for debug. Here's an
> > important
> > way to fix bugs that come from the firmware.
> > 
> > Documentation/acpi/initrd_table_override.txt
> I think we should message that this is for debug/development use.
> Ultimately, it's not the way to address firmware problems. Firmware
> needs to address that by shipping the correct(ed) tables :)

Thanks for your feedback.
According to following description in
Documentation/acpi/initrd_table_override.txt
"Complain to your platform/BIOS vendor if you find a bug which is so
severe that a workaround is not accepted in the Linux kernel. And this
facility allows you to upgrade the buggy tables before your
platform/BIOS vendor releases an upgraded BIOS binary."

I have changed the commit message to "Loading IORT table from initrd
can be used to fix severe firmware
IORT defects temporarily before platform/BIOS vendor releases an
upgraded BIOS binary..." in v4.

Detail Link is here,
https://patchwork.kernel.org/patch/10202391/

Thanks.
Shunyong.