Re: [PATCH v4 4/4] memory: emif: add device tree support to emif driver

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Aug 13, 2012 at 10:57:06AM +0530, Shilimkar, Santosh wrote:
> Greg,
> 
> On Wed, Jul 18, 2012 at 12:14 PM, Shilimkar, Santosh
> <santosh.shilimkar@ti.com> wrote:
> > On Tue, Jul 17, 2012 at 11:28 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >> On Tue, Jul 17, 2012 at 10:37:45PM +0530, Shilimkar, Santosh wrote:
> >>> On Tue, Jul 17, 2012 at 10:06 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >>> > On Mon, Jul 09, 2012 at 07:02:36PM +0530, Shilimkar, Santosh wrote:
> >>> >> Greg,
> >>> >>
> >
> > [..]
> >
> >>> >From 74688a87fd490909e9122bf757c0096480e9fc11 Mon Sep 17 00:00:00 2001
> >>> From: Aneesh V <aneesh@ti.com>
> >>> Date: Mon, 30 Jan 2012 20:06:30 +0530
> >>> Subject: [PATCH 4/4] memory: emif: add device tree support to emif driver
> >>>
> >>> Device tree support for the EMIF driver. LPDDR2 generic timings
> >>> extraction from device is managed using couple of helper
> >>> functions which can be used by other memory controller
> >>> drivers.
> >>>
> >>> Reviewed-by: Benoit Cousson <b-cousson@ti.com>
> >>> Reviewed-by: Grant Likely <grant.likely@secretlab.ca>
> >>> Tested-by: Lokesh Vutla <lokeshvutla@ti.com>
> >>> Signed-off-by: Aneesh V <aneesh@ti.com>
> >>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
> >>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >>> ---
> >>>  drivers/memory/Makefile    |    1 +
> >>>  drivers/memory/emif.c      |  182 +++++++++++++++++++++++++++++++++++++++++++-
> >>>  drivers/memory/of_memory.c |  153 +++++++++++++++++++++++++++++++++++++
> >>>  drivers/memory/of_memory.h |   36 +++++++++
> >>>  4 files changed, 371 insertions(+), 1 deletion(-)
> >>>  create mode 100644 drivers/memory/of_memory.c
> >>>  create mode 100644 drivers/memory/of_memory.h
> >>>
> >>> diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
> >>> index 42b3ce9..cd8486b 100644
> >>> --- a/drivers/memory/Makefile
> >>> +++ b/drivers/memory/Makefile
> >>> @@ -2,6 +2,7 @@
> >>>  # Makefile for memory devices
> >>>  #
> >>>
> >>> +obj-$(CONFIG_OF)             += of_memory.o
> >>>  obj-$(CONFIG_TI_EMIF)                += emif.o
> >>>  obj-$(CONFIG_TEGRA20_MC)     += tegra20-mc.o
> >>>  obj-$(CONFIG_TEGRA30_MC)     += tegra30-mc.o
> >>> diff --git a/drivers/memory/emif.c b/drivers/memory/emif.c
> >>> index 33a4396..06b4eb7 100644
> >>> --- a/drivers/memory/emif.c
> >>> +++ b/drivers/memory/emif.c
> >>> @@ -18,6 +18,7 @@
> >>>  #include <linux/platform_device.h>
> >>>  #include <linux/interrupt.h>
> >>>  #include <linux/slab.h>
> >>> +#include <linux/of.h>
> >>>  #include <linux/debugfs.h>
> >>>  #include <linux/seq_file.h>
> >>>  #include <linux/module.h>
> >>> @@ -25,6 +26,7 @@
> >>>  #include <linux/spinlock.h>
> >>>  #include <memory/jedec_ddr.h>
> >>>  #include "emif.h"
> >>> +#include "of_memory.h"
> >>>
> >>>  /**
> >>>   * struct emif_data - Per device static data for driver's use
> >>> @@ -49,6 +51,7 @@
> >>>   *                           frequency in effect at the moment)
> >>>   * @plat_data:                       Pointer to saved platform data.
> >>>   * @debugfs_root:            dentry to the root folder for EMIF in debugfs
> >>> + * @np_ddr:                  Pointer to ddr device tree node
> >>>   */
> >>>  struct emif_data {
> >>>       u8                              duplicate;
> >>> @@ -63,6 +66,7 @@ struct emif_data {
> >>>       struct emif_regs                *curr_regs;
> >>>       struct emif_platform_data       *plat_data;
> >>>       struct dentry                   *debugfs_root;
> >>> +     struct device_node              *np_ddr;
> >>>  };
> >>>
> >>>  static struct emif_data *emif1;
> >>> @@ -1148,6 +1152,168 @@ static int is_custom_config_valid(struct
> >>> emif_custom_configs *cust_cfgs,
> >>>       return valid;
> >>>  }
> >>>
> >>> +#if defined(CONFIG_OF)
> >>> +static void __init_or_module of_get_custom_configs(struct device_node *np_emif,
> >>> +             struct emif_data *emif)
> >>
> >> Why can't all of this code be in the of_memory.c file?
> >>
> > Primarily because the parameters are very much specific to EMIF
> > memory controller and won't be of much use for other memory controllers.
> >
> > Currently the information extracted from DT with these function is like:
> > - EMIF controller IP version : EMIF_4D or EMIF_4D5
> > - Which analog phy is integrated : EMIF_ATTILAPHY or EMIF_ATTILAPHY
> > - IP hardware interface: EMIF Low latency port or sys port interface.
> > - EMIF connections - Whether EMIF1 only, EMIF2 only or EMIF1 & EMIF2
> > - Memory connections to EMIF - Same type and size memories or asymmetric
> > - Chip select usage per controller: Whether CS0, CS1, CS0 & CS1
> > - ZQ calibration - Per chip select or enable EMIF dual calibration feature.
> > - Enable/disable EMIF Low power mode and temperature alerts.
> > - EMIF low power mode configuration:
> >       - Clock stop, self refresh, Deep power down.
> >       - Low power time out values for performance and power mode.
> >       - DDR frequency threshold to switch between power and
> > performance settings.
> > - EMIF temperature polling cycle configuration.
> >
> > As you can see these are very specific to the EMIF memory controller and hence
> > I didn't move them to of_memory.c
> >
> Do you have any more comment on this patch? If not, I can go ahead and
> post the refreshed version of the patch.

Please always do, I have no idea what this patch even contained anymore,
it was a few hundred patches ago that I've reviewed and I have no
recollection of it...

thanks,

greg k-h