Hi Brian,

-----Original Message-----
From: Brian Norris [mailto:computersforpeace@gmail.com]
Sent: Tuesday, February 11, 2014 3:40 AM
To: Hou Zhiqiang-B48286
Cc: linux-mtd@lists.infradead.org; linuxppc-dev@ozlabs.org; Wood Scott-
B07421; Hu Mingkai-B21284; linux-spi@vger.kernel.org
Subject: Re: [PATCH v2] mtd: m25p80: Make the name of mtd_info fixed
=20
On Sun, Jan 26, 2014 at 02:16:43PM +0800, Hou Zhiqiang wrote:

quoted

To give spi flash layout using "mtdparts=3D..." in cmdline, we must giv=

e

quoted

mtd_info a fixed name,because the cmdlinepart's parser will match the
name given in cmdline with the mtd_info.

Now, if use OF node, mtd_info's name will be spi->dev->name. It
consists of spi_master->bus_num, and the spi_master->bus_num maybe
dynamically fetched.
So, give the mtd_info a new fiexd name "name.cs", "name" is name of
spi_device_id and "cs" is chip-select in spi_dev.

Signed-off-by: Hou Zhiqiang <redacted>
---
v2:
 - add check for return value of function kasprintf.
 - whether the spi_master->bus_num is dynamical is determined by spi
   controller driver, and it can't be check in this driver. So, we can
   not initial the mtd_info's name by distinguishing the spi_master
   bus_num dynamically-allocated or not.

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How about spi->master->bus_num < 0 ?
=20

In spi slave driver, we can not see this case. The spi->master->bus_num=20
must be greater than 0, because before loading spi slave driver, the spi
controller driver will check spi->master->bus_num, if it is less than 0,
the spi controller driver will allocate a new bus_num dynamically. So it
is always greater than 0 in m25p80.c.

quoted

 drivers/mtd/devices/m25p80.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c

b/drivers/mtd/devices/m25p80.c index eb558e8..1f494d2 100644

--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c

@@ -1011,8 +1011,12 @@ static int m25p_probe(struct spi_device *spi)

 	if (data && data->name)
 		flash->mtd.name =3D data->name;
-	else
-		flash->mtd.name =3D dev_name(&spi->dev);
+	else {
+		flash->mtd.name =3D kasprintf(GFP_KERNEL, "%s.%d",
+				id->name, spi->chip_select);

=20
I don't think this name is specific enough. What if there are more than
one SPI controller? Then there could be one chip with the same chip-
select. You probably still need to incorporate the SPI master somehow,
even if it's not by using the bus number directly (because it's dynamic).

Yeah, you're right. Actually the bus_num is used to distinguish different
spi controller. If the controller driver give a dynamically-allocated
bus_num, yourself should take the risk to use mtdparts in command line.
I think, it is spi controller driver's responsibility to assign a
reasonable bus_num to make sure using command line mtdparts riskless, then
it is unnecessary to change mtdinfo's name.
=20

quoted

+		if (!flash->mtd.name)
+			return -ENOMEM;
+	}

 	flash->mtd.type =3D MTD_NORFLASH;
 	flash->mtd.writesize =3D 1;

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Brian
=20

Zhiqiang Hou