linux-kernel - Re: [PATCH] memory: omap-gpmc: fix multi-device handling on the same CS

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Message-ID: <8db143ce-d479-d7c8-bf85-f81d7a6e66d9@gmail.com>
Date:   Sat, 14 Jan 2023 13:44:41 +0900
From:   INAGAKI Hiroshi <musashino.open@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        rogerq@...nel.org, tony@...mide.com
Cc:     linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memory: omap-gpmc: fix multi-device handling on the same
 CS

Hi Krzysztof,

thank you for your review and sorry for my ugly patch.

On 2023/01/11 23:57, Krzysztof Kozlowski wrote:
> On 11/01/2023 15:13, INAGAKI Hiroshi wrote:
>> This patch fixes the handling of multiple devices on the same CS by
> Do not use "This commit/patch".
> https://elixir.bootlin.com/linux/v5.17.1/source/Documentation/process/submitting-patches.rst#L95
Okay, I'll improve.

>
>> replacing CS name to "name" of node instead of "full_name".
>>
>> In c2ade654dbf7d02f09ad491f5621fc321d4af96b
>> ("memory: omap-gpmc: Use of_node_name_eq for node name comparisons"),
> Use syntax: commit short SHA (".....") as pointed by checkpatch.
I see, I'll replace.

>
>> the name for setting to CS was replaced but it doesn't fit for the
>> comparison by of_node_name_eq.
>> In of_node_name_eq, the length for strncmp will be obtained from the
>> node that trying to register and it doesn't contain the length of
>> "@<cs>,<offset>".
> Skip explanation what is inside of_node_name_eq() but focus on what the
> driver is doing.
Okay, I'll improve it.

>
>> But the base name for comparison passed from
>> registered CS name contains the prefix,
> What is "the prefix"?
Ahh, it's not a prefix, but suffix...my mistake.

>
>>   then, that two lengths won't
>> match and false will be returned, and registration on the same CS
>> will be failed.
> Unfortunately, based on this, I don't get what is compare with what. I
> bet the issue is simple, but based on the description it does not look
> like that.
Indeed... I wrote it because I felt like I had to explain it in detail, 
but I made it unnecessarily complicated.
I'll improve and make it concise.

>
>> example (Century Systems MA-E350/N, AM3352):
>>
>> - Device Tree
>>
>>    /* memory mapped gpio controllers on GPMC */
>>    gpio@2,2 {
>>        reg = <2 0x2 0x1>; /* CS2, offset 0x2, IO size 0x1 */
>>        ...
>>    };
>>
>>    gpio@2,10 {
>>        reg = <2 0x10 0x1>; /* CS2, offset 0x10, IO size 0x1 */
>>        ...
>>    };
>>
>>    gpio@2,12 {
>>        reg = <2 0x12 0x1>; /* CS2, offset 0x12, IO size 0x1 */
>>        ...
>>    };
>>
>>    gpio@2,14 {
>>        reg = <2 0x14 0x1>; /* CS2, offset 0x14, IO size 0x1 */
>>        ...
>>    };
> Trim it, two entries might be enough to illustrate it.
Okay, I'll reduce.

>
>> - dmesg
>>
>>    [    1.596402] omap-gpmc 50000000.gpmc: cannot request GPMC CS 2
>>    [    1.596434] omap-gpmc 50000000.gpmc: failed to probe DT child 'gpio': -16
>>    [    1.596489] omap-gpmc 50000000.gpmc: cannot request GPMC CS 2
>>    [    1.596511] omap-gpmc 50000000.gpmc: failed to probe DT child 'gpio': -16
>>    [    1.596564] omap-gpmc 50000000.gpmc: cannot request GPMC CS 2
>>    [    1.596586] omap-gpmc 50000000.gpmc: failed to probe DT child 'gpio': -16
>>
>>    ("gpio@2,2" is ok, "gpio@2,10", "gpio@2,12", "gpio@...4" are fail)
>>
>> Fixes: c2ade654dbf7d02f09ad491f5621fc321d4af96b
>> ("memory: omap-gpmc: Use of_node_name_eq for node name comparisons")
> Also not correct tag. Run checkpatch.
>
> No blank lines.
I'll fix.

>
>> Signed-off-by: INAGAKI Hiroshi <musashino.open@...il.com>
>
>> ---
>>   drivers/memory/omap-gpmc.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
>> index d78f73db37c8..3e3e84e34795 100644
>> --- a/drivers/memory/omap-gpmc.c
>> +++ b/drivers/memory/omap-gpmc.c
>> @@ -2202,7 +2202,7 @@ static int gpmc_probe_generic_child(struct platform_device *pdev,
>>   		dev_err(&pdev->dev, "cannot request GPMC CS %d\n", cs);
>>   		return ret;
>>   	}
>> -	gpmc_cs_set_name(cs, child->full_name);
>> +	gpmc_cs_set_name(cs, child->name);
>>   
>>   	gpmc_read_settings_dt(child, &gpmc_s);
>>   	gpmc_read_timings_dt(child, &gpmc_t);
>>
>> base-commit: 13f35b3c72f4075e13a974f439b20b9e26f8f243
> Best regards,
> Krzysztof
>

I've completely forgot to run checkpatch.pl before sending...
Before sending the next patch, I will fix the points pointed out this 
time, read the guidelines carefully again and run checkpatch.

Regards,
Hiroshi