Received-SPF: Pass (protection.outlook.com: domain of xilinx.com designates
 149.199.62.198 as permitted sender) receiver=protection.outlook.com;
 client-ip=149.199.62.198; helo=xsj-pvapexch02.xlnx.xilinx.com;
Envelope-to: dwmw2@infradead.org,
 mdf@kernel.org,
 trix@redhat.com,
 devicetree@vger.kernel.org,
 linux-fpga@vger.kernel.org,
 linux-kernel@vger.kernel.org,
 robh@kernel.org
Subject: Re: [PATCH V2 XRT Alveo Infrastructure 4/9] of: create empty of root
To:     Rob Herring <robh@kernel.org>, Lizhi Hou <lizhi.hou@xilinx.com>
CC:     <linux-kernel@vger.kernel.org>, <linux-fpga@vger.kernel.org>,
        <maxz@xilinx.com>, <sonal.santan@xilinx.com>, <yliu@xilinx.com>,
        <michal.simek@xilinx.com>, <stefanos@xilinx.com>,
        <devicetree@vger.kernel.org>, <trix@redhat.com>, <mdf@kernel.org>,
        <dwmw2@infradead.org>, Max Zhen <max.zhen@xilinx.com>
References: <20211119222412.1092763-1-lizhi.hou@xilinx.com>
 <20211119222412.1092763-5-lizhi.hou@xilinx.com>
 <YaWFksVvfQQWqKcG@robh.at.kernel.org>
From:   Lizhi Hou <lizhi.hou@xilinx.com>
Message-ID: <eeeb4657-c936-096e-0cf8-afde2220f626@xilinx.com>
Date:   Tue, 30 Nov 2021 13:21:49 -0800
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.9.1
MIME-Version: 1.0
In-Reply-To: <YaWFksVvfQQWqKcG@robh.at.kernel.org>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Nov 2021 21:21:51.3751
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 628452c4-f1e1-4eac-34d8-08d9b4476d11
X-MS-Exchange-CrossTenant-Id: 657af505-d5df-48d0-8300-c31994686c5c
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=657af505-d5df-48d0-8300-c31994686c5c;Ip=[149.199.62.198];Helo=[xsj-pvapexch02.xlnx.xilinx.com]
X-MS-Exchange-CrossTenant-AuthSource: BN1NAM02FT027.eop-nam02.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH2PR02MB6824
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org


On 11/29/21 5:59 PM, Rob Herring wrote:
> On Fri, Nov 19, 2021 at 02:24:07PM -0800, Lizhi Hou wrote:
>> When OF_FLATTREE is selected and there is not a device tree, create an
>> empty device tree root node. of/unittest.c code is referenced.
> What does the last sentence mean? You copied the code? If so, that's a
> sign you should refactor the unittest code to use this.

I looked into unittest.c for how the of_root is created.  And you are 
right, this could should be unified with unittest.c. I will change it 
with next patch set.

Thanks,

Lizhi

>
>> Signed-off-by: Sonal Santan <sonal.santan@xilinx.com>
>> Signed-off-by: Max Zhen <max.zhen@xilinx.com>
>> Signed-off-by: Lizhi Hou <lizhi.hou@xilinx.com>
>> ---
>>   drivers/of/Makefile        |  2 +-
>>   drivers/of/fdt.c           | 20 ++++++++++++++++++++
>>   drivers/of/fdt_default.dts |  5 +++++
>>   drivers/of/of_private.h    |  5 +++++
>>   4 files changed, 31 insertions(+), 1 deletion(-)
>>   create mode 100644 drivers/of/fdt_default.dts
>>
>> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
>> index c13b982084a3..815f5220465b 100644
>> --- a/drivers/of/Makefile
>> +++ b/drivers/of/Makefile
>> @@ -2,7 +2,7 @@
>>   obj-y = base.o device.o platform.o property.o
>>   obj-$(CONFIG_OF_KOBJ) += kobj.o
>>   obj-$(CONFIG_OF_DYNAMIC) += dynamic.o
>> -obj-$(CONFIG_OF_FLATTREE) += fdt.o
>> +obj-$(CONFIG_OF_FLATTREE) += fdt.o fdt_default.dtb.o
>>   obj-$(CONFIG_OF_EARLY_FLATTREE) += fdt_address.o
>>   obj-$(CONFIG_OF_PROMTREE) += pdt.o
>>   obj-$(CONFIG_OF_ADDRESS)  += address.o
>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>> index d64445e43ceb..3d6e4543419e 100644
>> --- a/drivers/of/fdt.c
>> +++ b/drivers/of/fdt.c
>> @@ -481,6 +481,26 @@ void *of_fdt_unflatten_tree(const unsigned long *blob,
>>   }
>>   EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree);
>>
>> +static int __init of_fdt_root_init(void)
>> +{
>> +     struct device_node *np;
>> +
>> +     if (of_root)
>> +             return 0;
>> +
>> +     if (!of_fdt_unflatten_tree((const unsigned long *)__dtb_fdt_default_begin,
>> +                                NULL, &of_root)) {
>> +             pr_warn("%s: unflatten default tree failed\n", __func__);
>> +             return -ENODATA;
>> +     }
>> +
>> +     for_each_of_allnodes(np)
>> +             __of_attach_node_sysfs(np);
>> +
>> +     return 0;
>> +}
>> +late_initcall(of_fdt_root_init);
>> +
>>   /* Everything below here references initial_boot_params directly. */
>>   int __initdata dt_root_addr_cells;
>>   int __initdata dt_root_size_cells;
>> diff --git a/drivers/of/fdt_default.dts b/drivers/of/fdt_default.dts
>> new file mode 100644
>> index 000000000000..d1f12a76dfc6
>> --- /dev/null
>> +++ b/drivers/of/fdt_default.dts
>> @@ -0,0 +1,5 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/dts-v1/;
>> +
>> +/ {
>> +};
>> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
>> index 631489f7f8c0..47c6bb47ef25 100644
>> --- a/drivers/of/of_private.h
>> +++ b/drivers/of/of_private.h
>> @@ -41,6 +41,11 @@ extern struct mutex of_mutex;
>>   extern struct list_head aliases_lookup;
>>   extern struct kset *of_kset;
>>
>> +#if defined(CONFIG_OF_FLATTREE)
>> +extern u8 __dtb_fdt_default_begin[];
>> +extern u8 __dtb_fdt_default_end[];
>> +#endif
>> +
>>   #if defined(CONFIG_OF_DYNAMIC)
>>   extern int of_property_notify(int action, struct device_node *np,
>>                              struct property *prop, struct property *old_prop);
>> --
>> 2.27.0
>>
>>