[U-Boot] [PATCH] ppc4xx: Canyonlands: Fix USB host PHY reset sequence
Current de-assert reset is not sufficient for the USB PHY reset on some Canyonlands platforms. The patch adds an assert/de-assert sequence. This addresses a USB detection problem for devices attached prior to power-up. The delay lengths are needed for power to the PHY to stabilize.
Signed-off-by: Jeff Mann MannJ@embeddedplanet.com Signed-off-by: Dave Mitchell dmitchell@appliedmicro.com Acked-by: Tirumala Reddy Marri tmarri@appliedmicro.com --- board/amcc/canyonlands/canyonlands.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/board/amcc/canyonlands/canyonlands.c b/board/amcc/canyonlands/canyonlands.c index 13a0dac..bef12ae 100644 --- a/board/amcc/canyonlands/canyonlands.c +++ b/board/amcc/canyonlands/canyonlands.c @@ -177,8 +177,11 @@ int board_early_init_f(void) /* Remove NOR-FLASH, NAND-FLASH & EEPROM hardware write protection */ out_8((void *)CONFIG_SYS_BCSR_BASE + 5, 0);
- /* Enable USB host & USB-OTG */ + /* Enable USB host & USB-OTG;force assert,then de-assert PHY reset */ + out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 1); + mdelay(100); out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 0); + mdealy(100);
mtsdr(SDR0_SRST1, 0); /* Pull AHB out of reset default=1 */
Dear Dave Mitchell,
In message 1260821359-8705-1-git-send-email-dmitchell@appliedmicro.com you wrote:
Current de-assert reset is not sufficient for the USB PHY reset on some Canyonlands platforms. The patch adds an assert/de-assert sequence. This addresses a USB detection problem for devices attached prior to power-up. The delay lengths are needed for power to the PHY to stabilize.
Hm...
- /* Enable USB host & USB-OTG */
- /* Enable USB host & USB-OTG;force assert,then de-assert PHY reset */
- out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 1);
- mdelay(100); out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 0);
- mdealy(100);
It would have been nice if you had at least tried to compile that. "mdealy()" is a typo, right?
And do we really need 200 milliseconds delay?
Some customers who care about boot times will not be happy about such an aditional delay. You add this code do board_early_init_f() which always gets executed. But actually this is only needed when we want to use the USB port in U-Boot, right? So this should be added to the USB init code, and not to the common code.
Best regards,
Wolfgang Denk
Hi Wolfgang,
-----Original Message----- From: Wolfgang Denk [mailto:wd@denx.de] Sent: Monday, December 14, 2009 2:42 PM To: David Mitchell Cc: u-boot@lists.denx.de; Stefan Roese; Jeff Mann Subject: Re: [U-Boot] [PATCH] ppc4xx: Canyonlands: Fix USB host PHY reset sequence
- /* Enable USB host & USB-OTG */
- /* Enable USB host & USB-OTG;force assert,then de-assert PHY
reset */
- out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 1);
- mdelay(100); out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 0);
- mdealy(100);
It would have been nice if you had at least tried to compile that. "mdealy()" is a typo, right?
Ah, sorry about that. I had the patch hanging around and moved it up to the ToT by hand.
I'll fix and re-submit.
And do we really need 200 milliseconds delay?
I generated several versions for a remote team to test (I don't have the failing hardware). Only the 100ms version worked every time.
I did request a hardware investigation to clarify the 100ms delays. They reported the time was needed for the power to stabilize.
Some customers who care about boot times will not be happy about such an aditional delay. You add this code do board_early_init_f() which always gets executed. But actually this is only needed when we want to use the USB port in U-Boot, right? So this should be added to the USB init code, and not to the common code.
Actually we need the reset prior to Linux boot as well. Otherwise Linux will not discover attached devices. Which is the whole reason for the patch...
Best regards, -DM --------------------------------------------------------
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Dear David,
In message AC5E1C3367E37D44970B81A6ADD1DA2C087E7893@SDCEXCHANGE01.ad.amcc.com you wrote:
I generated several versions for a remote team to test (I don't have the failing hardware). Only the 100ms version worked every time.
I see :-(
Actually we need the reset prior to Linux boot as well. Otherwise Linux will not discover attached devices. Which is the whole reason for the patch...
No, we don't. Why should we add a delay for all systems, even when neither U-Boot not Linux will ever use any USB? For example ion boards where not even a USB connector is physically present on the hardware?
Please (re-) read the U-Boot Design Principles, item 2 "Keep it fast": http://www.denx.de/wiki/view/U-Boot/DesignPrinciples#2_Keep_it_Fast
If USB is not used in U-Boot itself, U-Boot shall not initialize it at all. And we should never impose restrictions or penalties (delays) on everybody for features that are used only by some.
Best regards,
Wolfgang Denk
Dear Stefan,
In message 1260821359-8705-1-git-send-email-dmitchell@appliedmicro.com Dave Mitchell wrote: ...
--- a/board/amcc/canyonlands/canyonlands.c +++ b/board/amcc/canyonlands/canyonlands.c @@ -177,8 +177,11 @@ int board_early_init_f(void) /* Remove NOR-FLASH, NAND-FLASH & EEPROM hardware write protection */ out_8((void *)CONFIG_SYS_BCSR_BASE + 5, 0);
- /* Enable USB host & USB-OTG */
- /* Enable USB host & USB-OTG;force assert,then de-assert PHY reset */
- out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 1);
- mdelay(100); out_8((void *)CONFIG_SYS_BCSR_BASE + 7, 0);
- mdealy(100);
We should get rid of this "CONFIG_SYS_BCSR_BASE + offset" stuff and use a proper C struct for this. What do you think?
Best regards,
Wolfgang Denk
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David Mitchell -
Wolfgang Denk