Re: [PATCH] memory: fsl_ifc: Make FSL_IFC config visible and selectable

Esben Haabendal
2024-05-27T07:47:18Z

Esben Haabendal <esben@geanix.com> writes:

> Krzysztof Kozlowski <krzk@kernel.org> writes:
>
>> On 27/05/2024 08:55, Esben Haabendal wrote:
>>> Krzysztof Kozlowski <krzk@kernel.org> writes:
>>>
>>>> On 24/05/2024 10:47, Esben Haabendal wrote:
>>>>> Krzysztof Kozlowski <krzk@kernel.org> writes:
>>>>>
>>>>>> On 23/05/2024 16:32, Esben Haabendal wrote:
>>>>>>> Krzysztof Kozlowski <krzk@kernel.org> writes:
>>>>>>>
>>>>>>>> On 23/05/2024 15:58, Esben Haabendal wrote:
>>>>>>>>> While use of fsl_ifc driver with NAND flash is fine, as the fsl_ifc_nand
>>>>>>>>> driver selects FSL_IFC automatically, we need the option to be selectable
>>>>>>>>> for platforms using fsl_ifc with NOR flash.
>>>>>>>>
>>>>>>>> Which driver is that?
>>>>>>>
>>>>>>> This is drivers/memory/fsl_ifc.o driver. It is for Integrated Flash
>>>>>>> Controller (IFC) from NXP. It is used in various Layerscape socs.
>>>>>>
>>>>>> ? I know that, I mean the NOR flash working here.
>>>>>
>>>>> Ah, sorry. The NOR flash I am using here is a Spansion S29AL016J.
>>>>>
>>>>>>>> Which DTS?
>>>>>>>
>>>>>>> It is for "fsl,ifc" compatible devices.
>>>>>>
>>>>>> That's not a NOR flash.
>>>>>
>>>>> Nope. The binding used for the NOR flash is "cfi-flash".
>>>>
>>>> And now let's get back to my original question. I asked for driver, not
>>>> device, and for DTS not compatible.
>>>
>>> You got me really confused now. I am not sure what you are asking me
>>> for, and why.
>>>
>>> I am sending a patch which changes to Kconfig for a memory controller
>>> driver. The change is AFAICS quite similar to commit be34f45f0d4a
>>> ("memory: omap-gpmc: Make OMAP_GPMC config visible and selectable").
>>>
>>> As for the NOR flash that in this situation is attached to the IFC
>>> controller, it is (as mentioned) Spansion S29AL016J. It is handled by
>>> the drivers/mtd/maps/physmap.o driver (CONFIG_MTD_PHYSMAP +
>>> CONFIG_MTD_PHYSMAP_OF)
>>
>> Thanks.
>>
>>>
>>> The DTS used to specify the NOR flash is
>>
>> Upstream DTS. I don't care about downstream.
>
> Upstream DTS is arch/arm/boot/dts/nxp/ls/ls1021a.dtsi
>
> Which has
>
> ifc: memory-controller@1530000 {
> compatible = "fsl,ifc";
> reg = <0x0 0x1530000 0x0 0x10000>;
> interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH>;
> status = "disabled";
> };
>
> The NOR flash is not specified in upstream DTS, as it is board and not
> SoC specific.
>
> I assume it is not considered bad practise to keep downstream DTS out of
> tree.
>
>>> &ifc {
>>> status = "okay";
>>> #address-cells = <2>;
>>> #size-cells = <1>;
>>> ranges = <0x0 0x0 0x0 0x60000000 0x00200000>;
>>>
>>> nor_flash: nor@0,0 {
>>> #address-cells = <1>;
>>> #size-cells = <1>;
>>> compatible = "cfi-flash";
>>> reg = <0x0 0x0 0x200000>;
>>> bank-width = <2>;
>>>
>>> partition@0 {
>>> reg = <0x000000 0x0f0000>;
>>> label = "boot0";
>>> };
>>> };
>>> };

Ok, I seem to still be confused as to what you want from me. If you are
saying that the kernel is not supposed to care about out-of-tree DTS
(and thereby any bootloader provided DTB), I would like to bring your
attention to arch/arm/boot/dts/nxp/ls/ls1021a-twr.dts in upstream:

&ifc {
#address-cells = <2>;
#size-cells = <1>;
/* NOR Flash on board */
ranges = <0x0 0x0 0x0 0x60000000 0x08000000>;
status = "okay";

nor@0,0 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "cfi-flash";
reg = <0x0 0x0 0x8000000>;
big-endian;
bank-width = <2>;
device-width = <1>;
};
};

This is basically identical to what I am using, and it will have the
same problem. It requires CONFIG_FSL_IFC enabled, which is not possible
(without enabling CONFIG_MTD_NAND_FSL_IFC). This board does not have
NAND, so I don't think it is reasonable to require keeping support for
it enabled to be able to use NOR flash.

/Esben