[PATCH 01/12] mtd: nand: davinci: store the core chipselect number in platform data

From: Bartosz Golaszewski <hidden>
Date: 2018-05-02 10:45:40
Also in: lkml

2018-05-01 12:29 GMT+02:00 Sekhar Nori [off-list ref]:

On Tuesday 01 May 2018 03:23 PM, Sekhar Nori wrote:

quoted

On Tuesday 01 May 2018 02:55 PM, Sekhar Nori wrote:

quoted

On Monday 30 April 2018 01:54 PM, Bartosz Golaszewski wrote:

quoted

From: Bartosz Golaszewski <redacted>

We have the 'ti,davinci-chipselect' property in the device tree, but
when using platform data the driver silently uses the id field of
struct platform_device as the chipselect. This is confusing and we
almost broke the nand support again recently after converting the
platform to common clock framework (which changed the device id in the
clock lookup - the problem is gone now that we no longer acquire the
clock in the nand driver.

This patch adds a new filed - core_chipsel - to the platform_data.

s/filed/field

quoted

Subsequent patches will convert the platforms to using this new field.

Can you add a comment for this new field too, like how we have for most
other fields?

Curious on what 'core' in core_chipsel means. Something to do with
chip-select offset we have on DA850?

Looks like you may have just picked the terminology from DaVinci NAND
driver (introduced back in 2009). But in this context, it means the
0-indexed chip-select number that of the asynchronous memory interface
to which the NAND device is connected.

So, may be a comment here will suffice.

This is what I committed:

I don't see it in your tree yet.

quoted hunk ↗ jump to hunk

--8<--
commit 533d93703fa717fdf74c4fb711c868c4fdc8b475 (HEAD -> refs/heads/v4.18/nand-cs-simplification)
Author:     Bartosz Golaszewski [off-list ref]
AuthorDate: Mon Apr 30 10:24:42 2018 +0200
Commit:     Sekhar Nori [off-list ref]
CommitDate: Tue May 1 15:57:47 2018 +0530

    mtd: nand: davinci: store the core chipselect number in platform data

    We have the 'ti,davinci-chipselect' property in the device tree, but
    when using platform data the driver silently uses the id field of
    struct platform_device as the chipselect. This is confusing and we
    almost broke the nand support again recently after converting the
    platform to common clock framework (which changed the device id in the
    clock lookup - the problem is gone now that we no longer acquire the
    clock in the nand driver.

    This patch adds a new field - core_chipsel - to the platform_data.
    Subsequent patches will convert the platforms to using this new field.

    Signed-off-by: Bartosz Golaszewski [off-list ref]
    Signed-off-by: Sekhar Nori [off-list ref]

diff --git a/include/linux/platform_data/mtd-davinci.h b/include/linux/platform_data/mtd-davinci.h
index f1a2cf655bdb..1bbfa27cccb4 100644
--- a/include/linux/platform_data/mtd-davinci.h
+++ b/include/linux/platform_data/mtd-davinci.h

@@ -56,6 +56,16 @@ struct davinci_nand_pdata {          /* platform_data */
        uint32_t                mask_ale;
        uint32_t                mask_cle;

+       /*
+        * 0-indexed chip-select number of the asynchronous
+        * interface to which the NAND device has been connected.
+        *
+        * So, if you have NAND connected to CS3 of DA850, you
+        * will pass '1' here. Since the asynchronous interface
+        * on DA850 starts from CS2.
+        */

Maybe we should add that on all other DaVinci SoCs the async interface
starts from CS0?

+       uint32_t                core_chipsel;
+
        /* for packages using two chipselects */
        uint32_t                mask_chipsel;

Thanks,
Bart

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