lkml.org 
[lkml]   [2012]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v4 0/7] Add TI EMIF SDRAM controller driver
From
Hi,

On 3/17/12, Aneesh V <aneesh@ti.com> 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 Dynamic Voltage and Frequency Scaling (DVFS).
> This can not be done now as DVFS support is not available in
> the mainline yet.
Do you see the devfreq? it's designed for non-cpu device frequency.
It's role is similar with cpufreq.

Now samsung exynos uses devfreq for DRAM bus frequency.

Thank you,
Kyungmin Park
>
> 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.
> - Tested the driver as a module
>
> Cc: Greg KH <greg@kroah.com>
>
> v4:
> - Converted instances of EXPORT_SYMBOL to EXPORT_SYMBOL_GPL
> - Removed un-necessary "#ifndef __ASSEMBLY__'
> - Minor formatting fix
>
> v2:
> - Fixed a bug found in the implementation of errata i728
> workaround
> - Fixed the value of frequency printed in debugfs
> - Dropped the hwmod patch as Paul has already posted a
> a hwmod series [1] that adds hwmod for EMIF
> - Converted instances of __init to __init_or_module
>
> [1] http://thread.gmane.org/gmane.linux.ports.arm.omap/72855
>
> Aneesh V (7):
> misc: ddr: add LPDDR2 data from JESD209-2
> misc: emif: add register definitions for EMIF
> misc: emif: add basic infrastructure for EMIF driver
> misc: emif: handle frequency and voltage change events
> misc: emif: add interrupt and temperature handling
> misc: emif: add one-time settings
> misc: emif: add debugfs entries for emif
>
> Documentation/misc-devices/ti-emif.txt | 58 ++
> drivers/misc/Kconfig | 12 +
> drivers/misc/Makefile | 1 +
> drivers/misc/emif.c | 1670
> +++++++++++++++++++++++++++++++
> drivers/misc/emif.h | 589 +++++++++++
> include/linux/platform_data/emif_plat.h | 128 +++
> include/misc/jedec_ddr.h | 175 ++++
> lib/Kconfig | 8 +
> lib/Makefile | 2 +
> lib/jedec_ddr_data.c | 135 +++
> 10 files changed, 2778 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/misc-devices/ti-emif.txt
> create mode 100644 drivers/misc/emif.c
> create mode 100644 drivers/misc/emif.h
> create mode 100644 include/linux/platform_data/emif_plat.h
> create mode 100644 include/misc/jedec_ddr.h
> create mode 100644 lib/jedec_ddr_data.c
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>


\
 
 \ /
  Last update: 2012-03-17 07:13    [W:0.159 / U:0.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site