[U-Boot] [PATCH 1/2] imx: mx7: fix potential overflow in imx_ddr_size()

[U-Boot] [PATCH 1/2] imx: mx7: fix potential overflow in imx_ddr_size()

[Marcel Ziswiler]

From: Marcel Ziswiler <marcel.ziswiler@toradex.com>

The imx_ddr_size() function may overflow as it is possible to kind of
over provision the DDR controller. Fix this by capping it to 2 GB which
is the maximum allowed size as per reference manual.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

--

 arch/arm/mach-imx/mx7/ddr.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/mach-imx/mx7/ddr.c b/arch/arm/mach-imx/mx7/ddr.c
index f19aeb8042..9713835bf2 100644
--- a/arch/arm/mach-imx/mx7/ddr.c
+++ b/arch/arm/mach-imx/mx7/ddr.c
@@ -196,5 +196,9 @@ unsigned int imx_ddr_size(void)
 	if (field_val <= 29)
 		bits++;
 
+	/* cap to max 2 GB */
+	if (bits > 31)
+		bits = 31;
+
 	return 1 << bits;
 }
-- 
2.14.4

[U-Boot] [PATCH 2/2] colibri_imx7: prime get_ram_size() using imx_ddr_size()

[Marcel Ziswiler]

From: Fabio Estevam <festevam@gmail.com>

Rather than passing a hardcoded maxsize to the generic get_ram_size()
function use the i.MX 7 specific imx_ddr_size() function, which extracts
the memory size at runtime by reading the DDR controller registers.

This is a purely cosmetic change as the generic get_ram_size() function
already took care of properly automatically detecting 256MB, 512MB or 1GB
modules.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

---

 board/toradex/colibri_imx7/colibri_imx7.c | 2 +-
 include/configs/colibri_imx7.h            | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/board/toradex/colibri_imx7/colibri_imx7.c b/board/toradex/colibri_imx7/colibri_imx7.c
index 2b7591eb00..a4c99626b4 100644
--- a/board/toradex/colibri_imx7/colibri_imx7.c
+++ b/board/toradex/colibri_imx7/colibri_imx7.c
@@ -52,7 +52,7 @@ DECLARE_GLOBAL_DATA_PTR;
 
 int dram_init(void)
 {
-	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, PHYS_SDRAM_SIZE);
+	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, imx_ddr_size());
 
 	return 0;
 }
diff --git a/include/configs/colibri_imx7.h b/include/configs/colibri_imx7.h
index ff6bd678cf..02849ba35f 100644
--- a/include/configs/colibri_imx7.h
+++ b/include/configs/colibri_imx7.h
@@ -14,7 +14,6 @@
 #include "mx7_common.h"
 
 /*#define CONFIG_DBG_MONITOR*/
-#define PHYS_SDRAM_SIZE			SZ_1G
 
 /* Size of malloc() pool */
 #define CONFIG_SYS_MALLOC_LEN		(32 * SZ_1M)
-- 
2.14.4

[U-Boot] [PATCH 1/2] imx: mx7: fix potential overflow in imx_ddr_size()

[Fabio Estevam]

Hi Marcel,

On Wed, Sep 19, 2018 at 8:01 AM, Marcel Ziswiler <marcel@ziswiler.com> wrote:
> From: Marcel Ziswiler <marcel.ziswiler@toradex.com>
>
> The imx_ddr_size() function may overflow as it is possible to kind of
> over provision the DDR controller. Fix this by capping it to 2 GB which
> is the maximum allowed size as per reference manual.
>
> Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

Looks good, thanks:

Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

[U-Boot] [PATCH 2/2] colibri_imx7: prime get_ram_size() using imx_ddr_size()

[Fabio Estevam]

Hi Marcel,

On Wed, Sep 19, 2018 at 8:01 AM, Marcel Ziswiler <marcel@ziswiler.com> wrote:
> From: Fabio Estevam <festevam@gmail.com>
>
> Rather than passing a hardcoded maxsize to the generic get_ram_size()
> function use the i.MX 7 specific imx_ddr_size() function, which extracts
> the memory size at runtime by reading the DDR controller registers.
>
> This is a purely cosmetic change as the generic get_ram_size() function
> already took care of properly automatically detecting 256MB, 512MB or 1GB
> modules.
>
> Signed-off-by: Fabio Estevam <festevam@gmail.com>
> Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

Thanks for the respin:

Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

[U-Boot] [PATCH 2/2] colibri_imx7: prime get_ram_size() using imx_ddr_size()

[Stefan Agner]

Hi,

On 9/19/18 4:01 AM, Marcel Ziswiler wrote:
> From: Fabio Estevam <festevam@gmail.com>
> 
> Rather than passing a hardcoded maxsize to the generic get_ram_size()
> function use the i.MX 7 specific imx_ddr_size() function, which extracts
> the memory size at runtime by reading the DDR controller registers.
> 
> This is a purely cosmetic change as the generic get_ram_size() function
> already took care of properly automatically detecting 256MB, 512MB or 1GB
> modules.
> 
> Signed-off-by: Fabio Estevam <festevam@gmail.com>
> Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

Hm, with that we take the MMDC register information as the upper bound, and use regular U-Boot get_ram_size() to determine size by poking memory addresses. Seems sensible.

Acked-by: Stefan Agner <stefan.agner@toradex.com>

Fabio, I guess other boards use SPL to use different MMDC configuration for different memory size? Is there a downside doing this size over-provisioning? 

--
Stefan

> 
> ---
> 
>  board/toradex/colibri_imx7/colibri_imx7.c | 2 +-
>  include/configs/colibri_imx7.h            | 1 -
>  2 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/board/toradex/colibri_imx7/colibri_imx7.c b/board/toradex/colibri_imx7/colibri_imx7.c
> index 2b7591eb00..a4c99626b4 100644
> --- a/board/toradex/colibri_imx7/colibri_imx7.c
> +++ b/board/toradex/colibri_imx7/colibri_imx7.c
> @@ -52,7 +52,7 @@ DECLARE_GLOBAL_DATA_PTR;
>  
>  int dram_init(void)
>  {
> -	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, PHYS_SDRAM_SIZE);
> +	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, imx_ddr_size());
>  
>  	return 0;
>  }
> diff --git a/include/configs/colibri_imx7.h b/include/configs/colibri_imx7.h
> index ff6bd678cf..02849ba35f 100644
> --- a/include/configs/colibri_imx7.h
> +++ b/include/configs/colibri_imx7.h
> @@ -14,7 +14,6 @@
>  #include "mx7_common.h"
>  
>  /*#define CONFIG_DBG_MONITOR*/
> -#define PHYS_SDRAM_SIZE			SZ_1G
>  
>  /* Size of malloc() pool */
>  #define CONFIG_SYS_MALLOC_LEN		(32 * SZ_1M)
> 

[U-Boot] [PATCH 2/2] colibri_imx7: prime get_ram_size() using imx_ddr_size()

[Fabio Estevam]

Hi Stefan,

On Wed, Sep 19, 2018 at 12:48 PM, Stefan Agner <stefan.agner@toradex.com> wrote:

> Hm, with that we take the MMDC register information as the upper bound, and use regular U-Boot get_ram_size() to determine size by poking memory addresses. Seems sensible.
>
> Acked-by: Stefan Agner <stefan.agner@toradex.com>
>
> Fabio, I guess other boards use SPL to use different MMDC configuration for different memory size? Is there a downside doing this size over-provisioning?

That's correct: the imx7 boards that use imx_ddr_size() are
cl-som-imx7 and pico-imx7d, which uses SPL and provide different MMDC
configuration depending on the memory density.

I don't see a downside in doing this over-provisioning.

Regards,

Fabio Estevam