Re: [U-Boot] [PATCH] usb: dwc2: Reduce data buffer size to 16kB

[Marek Vasut]

On 02/21/2018 10:48 AM, Alexey Brodkin wrote:
> If we use hardware with very small RAM (let's consider just a couple
> of hundreds of kB but not megabytes) it is not super convenient to lose
> 64kB for statically allocated bufer which most probably won't be used
> as big as it is. Typically we'll have much shorter data packages to
> excahnge and in the worst case longer packets will be split on separate
> transactions.
> 
> Signed-off-by: Alexey Brodkin 
> Cc: Marek Vasut 

I think it does make sense to make this configurable with 64 kiB as
default and tweak your platform to 16 kiB in it's defconfig.

> ---
>  drivers/usb/host/dwc2.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
> index 0efe645044c5..20cd4a6d3d55 100644
> --- a/drivers/usb/host/dwc2.c
> +++ b/drivers/usb/host/dwc2.c
> @@ -25,7 +25,7 @@ DECLARE_GLOBAL_DATA_PTR;
>  #define DWC2_HC_CHANNEL  0
>  
>  #define DWC2_STATUS_BUF_SIZE 64
> -#define DWC2_DATA_BUF_SIZE   (64 * 1024)
> +#define DWC2_DATA_BUF_SIZE   (16 * 1024)
>  
>  #define MAX_DEVICE   16
>  #define MAX_ENDPOINT 16
> 


-- 
Best regards,
Marek Vasut
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Re: [U-Boot] [PATCH] usb: dwc2: Reduce data buffer size to 16kB

[Calvin Johnson]

> -Original Message-
> From: U-Boot [mailto:u-boot-boun...@lists.denx.de] On Behalf Of Alexey
> Brodkin
> Sent: Wednesday, February 21, 2018 3:18 PM
> To: u-boot@lists.denx.de
> Cc: Marek Vasut <ma...@denx.de>; Alexey Brodkin
> <alexey.brod...@synopsys.com>
> Subject: [U-Boot] [PATCH] usb: dwc2: Reduce data buffer size to 16kB
> 
> If we use hardware with very small RAM (let's consider just a couple
> of hundreds of kB but not megabytes) it is not super convenient to lose
> 64kB for statically allocated bufer which most probably won't be used
> as big as it is. Typically we'll have much shorter data packages to
> excahnge and in the worst case longer packets will be split on separate

s/ excahnge /exchange

Regards
Calvin
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[U-Boot] [PATCH] usb: dwc2: Reduce data buffer size to 16kB

[Alexey Brodkin]

If we use hardware with very small RAM (let's consider just a couple
of hundreds of kB but not megabytes) it is not super convenient to lose
64kB for statically allocated bufer which most probably won't be used
as big as it is. Typically we'll have much shorter data packages to
excahnge and in the worst case longer packets will be split on separate
transactions.

Signed-off-by: Alexey Brodkin 
Cc: Marek Vasut 
---
 drivers/usb/host/dwc2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index 0efe645044c5..20cd4a6d3d55 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -25,7 +25,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #define DWC2_HC_CHANNEL0
 
 #define DWC2_STATUS_BUF_SIZE   64
-#define DWC2_DATA_BUF_SIZE (64 * 1024)
+#define DWC2_DATA_BUF_SIZE (16 * 1024)
 
 #define MAX_DEVICE 16
 #define MAX_ENDPOINT   16
-- 
2.14.3

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