Messages in this thread | | | Subject | Re: [PATCH v4 10/10] mtd: rawnand: stm32_fmc2: get resources from parent node | From | Christophe Kerello <> | Date | Mon, 11 May 2020 14:47:09 +0200 |
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Hi Miquel,
On 5/11/20 1:59 PM, Miquel Raynal wrote: > Hi Christophe, > > Christophe Kerello <christophe.kerello@st.com> wrote on Mon, 11 May > 2020 12:21:03 +0200: > >> Hi Miquel, >> >> On 5/11/20 11:18 AM, Miquel Raynal wrote: >>> Hi Christophe, >>> >>> Christophe Kerello <christophe.kerello@st.com> wrote on Wed, 6 May 2020 >>> 11:11:19 +0200: >>> >>>> FMC2 EBI support has been added. Common resources (registers base >>>> and clock) are now shared between the 2 drivers. It means that the >>>> common resources should now be found in the parent device when EBI >>>> node is available. >>>> >>>> Signed-off-by: Christophe Kerello <christophe.kerello@st.com> >>>> --- >>> >>> [...] >>> >>>> + >>>> +static bool stm32_fmc2_nfc_check_for_parent(struct platform_device *pdev) >>>> +{ >>>> + u32 i; >>>> + int nb_resources = 0; >>>> + >>>> + /* Count the number of resources in reg property */ >>>> + for (i = 0; i < pdev->num_resources; i++) { >>>> + struct resource *res = &pdev->resource[i]; >>>> + >>>> + if (resource_type(res) == IORESOURCE_MEM) >>>> + nb_resources++; >>>> + } >>>> + >>>> + /* Each CS needs 3 resources defined (data, cmd and addr) */ >>>> + if (nb_resources % 3) >>>> + return false; >>>> + >>>> + return true; >>>> +} >>> >>> This function looks fragile. Why not just checking the compatible >>> string of the parent node? >>> >> >> Yes, it is another way to check that we have an EBI parent node. >> >> In this implementation, I was checking the number of reg tuples. >> In case we have 6, it means that the register base address is defined in the parent node (EBI node). >> In case we have 7, it means that the register base address is defined in the current node (NFC node). > > Yes, I understand what you are doing, but I kind of dislike the logic. > Relying on the number of reg tuples is something that can be done (I > used it myself one time), but I think this is more a hack that you do > when you have no other way to differentiate. I guess the proper way > would be to look at the parent's compatible. If it matches what you > expect, then you can store the dev->of_node->parent->dev somewhere in > your controller's structure and then use it to initialize the clock and > regmap. This way you don't have to move anything else in the probe path. >
OK, I will check the compatible string of the parent device using of_device_is_compatible API in v5. In case of the parent is found, I will add it in the structure of the controller (dev_parent). I will rely on this field only to get the common resources (the register base address and the clock) in the NFC node or in the EBI node.
Regards, Christophe Kerello.
> > Thanks, > Miquèl >
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