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    SubjectRe: [RFC PATCH 0/8] Add TI EMIF SDRAM controller driver
    On Thu, Feb 16, 2012 at 04:21:11PM +0530, Santosh Shilimkar wrote:
    > Andrew, Greg,
    >
    > On Saturday 04 February 2012 05:46 PM, Aneesh V wrote:
    > > Add a driver for the EMIF SDRAM controller used in TI SoCs
    > >
    > > EMIF is an SDRAM controller that supports, based on its revision,
    > > one or more of LPDDR2/DDR2/DDR3 protocols.This driver adds support
    > > for LPDDR2.
    > >
    > > The driver supports the following features:
    > > - Calculates the DDR AC timing parameters to be set in EMIF
    > > registers using data from the device data-sheets and based
    > > on the DDR frequency. If data from data-sheets is not available
    > > default timing values from the JEDEC spec are used. These
    > > will be safe, but not necessarily optimal
    > > - API for changing timings during DVFS or at boot-up
    > > - Temperature alert configuration and handling of temperature
    > > alerts, if any for LPDDR2 devices
    > > * temperature alert is based on periodic polling of MR4 mode
    > > register in DDR devices automatically performed by hardware
    > > * timings are de-rated and brought back to nominal when
    > > temperature raises and falls respectively
    > > - Cache of calculated register values to avoid re-calculating
    > > them
    > >
    > > The driver will need some minor updates when it is eventually
    > > integrated with DVFS. This can not be done now as DVFS support
    > > is not available yet in mainline.
    > >
    > > Discussions with Santosh Shilimkar <santosh.shilimkar@ti.com>
    > > were immensely helpful in shaping up the interfaces. Vibhore Vardhan
    > > <vvardhan@gmail.com> did the initial code snippet for thermal
    > > handling.
    > >
    > > Testing:
    > > - The driver is tested on OMAP4430 SDP.
    > > - The driver in a slightly adapted form is also tested on OMAP5.
    > > - Since mainline kernel doesn't have DVFS support yet,
    > > testing was done using a test module.
    > > - Temperature alert handling was tested with simulated interrupts
    > > and faked temperature values as testing all cases in real-life
    > > scenarios is difficult.
    > >
    > [...]
    >
    > > arch/arm/mach-omap2/omap_hwmod_44xx_data.c | 110 ++
    > > drivers/misc/Kconfig | 20 +
    > > drivers/misc/Makefile | 2 +
    > > drivers/misc/emif.c | 1522 ++++++++++++++++++++++++++++
    > > drivers/misc/emif_regs.h | 461 +++++++++
    > > drivers/misc/jedec_ddr_data.c | 141 +++
    > > include/linux/emif.h | 257 +++++
    > > include/linux/jedec_ddr.h | 174 ++++
    >
    > Any suggestion on where this driver can reside. It's a memory
    > controller driver which supports standard DDR functionality
    > as per JDEC specs including thermal alert. On top of
    > that it does support DVFS using the TI PRCM IP block.

    I don't know what any of those TLA words mean, so I really can't suggest
    where this code should go. But just from this diffstat, it looks like
    you are creating a new user/kernel interface, without documenting it
    anywhere, which isn't ok.

    greg k-h


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