[v2] clk: aspeed: Mark lclk (LPC) and espiclk (eSPI) as critical

Message ID 20181204185054.24053-1-jae.hyun.yoo@linux.intel.com
State Not Applicable, archived
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  • [v2] clk: aspeed: Mark lclk (LPC) and espiclk (eSPI) as critical
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Commit Message

Jae Hyun Yoo Dec. 4, 2018, 6:50 p.m.
These interfaces are used by host to talk to BMC, and the clock
source is from the host, usually from PCH. So this commit marks
the lclk as critical to make it able to be enabled. Also, it marks
espiclk too because eSPI is sharing the same interface with LPC.

Fixes: 15ed8ce5f84e ("clk: aspeed: Register gated clocks")
Cc: stable@vger.kernel.org
Cc: Joel Stanley <joel@jms.id.au>
Cc: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
---
 drivers/clk/clk-aspeed.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Stephen Boyd Dec. 4, 2018, 8:50 p.m. | #1
Quoting Jae Hyun Yoo (2018-12-04 10:50:53)
> These interfaces are used by host to talk to BMC, and the clock
> source is from the host, usually from PCH. So this commit marks
> the lclk as critical to make it able to be enabled. Also, it marks
> espiclk too because eSPI is sharing the same interface with LPC.
> 
> Fixes: 15ed8ce5f84e ("clk: aspeed: Register gated clocks")
> Cc: stable@vger.kernel.org
> Cc: Joel Stanley <joel@jms.id.au>
> Cc: Andrew Jeffery <andrew@aj.id.au>
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> ---
>  drivers/clk/clk-aspeed.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
> index 596136793fc4..df9504427246 100644
> --- a/drivers/clk/clk-aspeed.c
> +++ b/drivers/clk/clk-aspeed.c
> @@ -95,7 +95,7 @@ static const struct aspeed_gate_data aspeed_gates[] = {
>         [ASPEED_CLK_GATE_DCLK] =        {  5, -1, "dclk-gate",          NULL,   CLK_IS_CRITICAL }, /* DAC */
>         [ASPEED_CLK_GATE_REFCLK] =      {  6, -1, "refclk-gate",        "clkin", CLK_IS_CRITICAL },
>         [ASPEED_CLK_GATE_USBPORT2CLK] = {  7,  3, "usb-port2-gate",     NULL,   0 }, /* USB2.0 Host port 2 */
> -       [ASPEED_CLK_GATE_LCLK] =        {  8,  5, "lclk-gate",          NULL,   0 }, /* LPC */
> +       [ASPEED_CLK_GATE_LCLK] =        {  8,  5, "lclk-gate",          NULL,   CLK_IS_CRITICAL }, /* LPC clock from host. No parent dependency */

What does "No parent dependency" mean? I was hoping to see something
like the commit text, "lclk is used to talk to BMC which can happen at
anytime" or something like that.
Joel Stanley Dec. 4, 2018, 8:51 p.m. | #2
Hi Jae,

On Wed, 5 Dec 2018 at 05:20, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
>
> These interfaces are used by host to talk to BMC, and the clock
> source is from the host, usually from PCH. So this commit marks
> the lclk as critical to make it able to be enabled. Also, it marks
> espiclk too because eSPI is sharing the same interface with LPC.

While this is true on the platform you have in mind, on other
platforms this is not the case. They do not use eSPI, and LCLK is
enabled by the driver that is used to configure LPC
(drivers/misc/aspeed-lpc-ctrl.c):

 lpc_ctrl: lpc-ctrl@0 {
     compatible = "aspeed,ast2400-lpc-ctrl";
     reg = <0x0 0x80>;
     clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
 }

I wonder if we need a device tree binding to describe which clocks are critical.

Stephen, please don't merge this patch yet.

Cheers,

Joel


>
> Fixes: 15ed8ce5f84e ("clk: aspeed: Register gated clocks")
> Cc: stable@vger.kernel.org
> Cc: Joel Stanley <joel@jms.id.au>
> Cc: Andrew Jeffery <andrew@aj.id.au>
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> ---
>  drivers/clk/clk-aspeed.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
> index 596136793fc4..df9504427246 100644
> --- a/drivers/clk/clk-aspeed.c
> +++ b/drivers/clk/clk-aspeed.c
> @@ -95,7 +95,7 @@ static const struct aspeed_gate_data aspeed_gates[] = {
>         [ASPEED_CLK_GATE_DCLK] =        {  5, -1, "dclk-gate",          NULL,   CLK_IS_CRITICAL }, /* DAC */
>         [ASPEED_CLK_GATE_REFCLK] =      {  6, -1, "refclk-gate",        "clkin", CLK_IS_CRITICAL },
>         [ASPEED_CLK_GATE_USBPORT2CLK] = {  7,  3, "usb-port2-gate",     NULL,   0 }, /* USB2.0 Host port 2 */
> -       [ASPEED_CLK_GATE_LCLK] =        {  8,  5, "lclk-gate",          NULL,   0 }, /* LPC */
> +       [ASPEED_CLK_GATE_LCLK] =        {  8,  5, "lclk-gate",          NULL,   CLK_IS_CRITICAL }, /* LPC clock from host. No parent dependency */
>         [ASPEED_CLK_GATE_USBUHCICLK] =  {  9, 15, "usb-uhci-gate",      NULL,   0 }, /* USB1.1 (requires port 2 enabled) */
>         [ASPEED_CLK_GATE_D1CLK] =       { 10, 13, "d1clk-gate",         NULL,   0 }, /* GFX CRT */
>         [ASPEED_CLK_GATE_YCLK] =        { 13,  4, "yclk-gate",          NULL,   0 }, /* HAC */
> @@ -103,7 +103,7 @@ static const struct aspeed_gate_data aspeed_gates[] = {
>         [ASPEED_CLK_GATE_UART1CLK] =    { 15, -1, "uart1clk-gate",      "uart", 0 }, /* UART1 */
>         [ASPEED_CLK_GATE_UART2CLK] =    { 16, -1, "uart2clk-gate",      "uart", 0 }, /* UART2 */
>         [ASPEED_CLK_GATE_UART5CLK] =    { 17, -1, "uart5clk-gate",      "uart", 0 }, /* UART5 */
> -       [ASPEED_CLK_GATE_ESPICLK] =     { 19, -1, "espiclk-gate",       NULL,   0 }, /* eSPI */
> +       [ASPEED_CLK_GATE_ESPICLK] =     { 19, -1, "espiclk-gate",       NULL,   CLK_IS_CRITICAL }, /* eSPI clock from host. No parent dependency */
>         [ASPEED_CLK_GATE_MAC1CLK] =     { 20, 11, "mac1clk-gate",       "mac",  0 }, /* MAC1 */
>         [ASPEED_CLK_GATE_MAC2CLK] =     { 21, 12, "mac2clk-gate",       "mac",  0 }, /* MAC2 */
>         [ASPEED_CLK_GATE_RSACLK] =      { 24, -1, "rsaclk-gate",        NULL,   0 }, /* RSA */
> --
> 2.7.4
>
Stephen Boyd Dec. 4, 2018, 8:54 p.m. | #3
Quoting Joel Stanley (2018-12-04 12:51:43)
> Hi Jae,
> 
> On Wed, 5 Dec 2018 at 05:20, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
> >
> > These interfaces are used by host to talk to BMC, and the clock
> > source is from the host, usually from PCH. So this commit marks
> > the lclk as critical to make it able to be enabled. Also, it marks
> > espiclk too because eSPI is sharing the same interface with LPC.
> 
> While this is true on the platform you have in mind, on other
> platforms this is not the case. They do not use eSPI, and LCLK is
> enabled by the driver that is used to configure LPC
> (drivers/misc/aspeed-lpc-ctrl.c):
> 
>  lpc_ctrl: lpc-ctrl@0 {
>      compatible = "aspeed,ast2400-lpc-ctrl";
>      reg = <0x0 0x80>;
>      clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
>  }
> 
> I wonder if we need a device tree binding to describe which clocks are critical.

A binding to describe critical clks has been rejected in the past. I
don't think we need to have it here either? More information on why
things are being marked critical will be helpful to see if we need to
re-open that discussion again.

> 
> Stephen, please don't merge this patch yet.
> 

Sure.
Jae Hyun Yoo Dec. 5, 2018, 3:04 p.m. | #4
On 12/4/2018 2:54 PM, Stephen Boyd wrote:
> Quoting Joel Stanley (2018-12-04 12:51:43)
>> Hi Jae,
>>
>> On Wed, 5 Dec 2018 at 05:20, Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com> wrote:
>>>
>>> These interfaces are used by host to talk to BMC, and the clock
>>> source is from the host, usually from PCH. So this commit marks
>>> the lclk as critical to make it able to be enabled. Also, it marks
>>> espiclk too because eSPI is sharing the same interface with LPC.
>>
>> While this is true on the platform you have in mind, on other
>> platforms this is not the case. They do not use eSPI, and LCLK is
>> enabled by the driver that is used to configure LPC
>> (drivers/misc/aspeed-lpc-ctrl.c):
>>
>>   lpc_ctrl: lpc-ctrl@0 {
>>       compatible = "aspeed,ast2400-lpc-ctrl";
>>       reg = <0x0 0x80>;
>>       clocks = <&syscon ASPEED_CLK_GATE_LCLK>;
>>   }
>>
>> I wonder if we need a device tree binding to describe which clocks are critical.
> 
> A binding to describe critical clks has been rejected in the past. I
> don't think we need to have it here either? More information on why
> things are being marked critical will be helpful to see if we need to
> re-open that discussion again.
> 
>>
>> Stephen, please don't merge this patch yet.
>>
> 
> Sure.
> 

Hi Stephen and Joel,

Thanks for blocking this patch. We checked that LCLK gate can be opened
by enabling lpc-ctrl node without using this change. Please drop this
patch.

Thanks,
Jae

Patch

diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c
index 596136793fc4..df9504427246 100644
--- a/drivers/clk/clk-aspeed.c
+++ b/drivers/clk/clk-aspeed.c
@@ -95,7 +95,7 @@  static const struct aspeed_gate_data aspeed_gates[] = {
 	[ASPEED_CLK_GATE_DCLK] =	{  5, -1, "dclk-gate",		NULL,	CLK_IS_CRITICAL }, /* DAC */
 	[ASPEED_CLK_GATE_REFCLK] =	{  6, -1, "refclk-gate",	"clkin", CLK_IS_CRITICAL },
 	[ASPEED_CLK_GATE_USBPORT2CLK] =	{  7,  3, "usb-port2-gate",	NULL,	0 }, /* USB2.0 Host port 2 */
-	[ASPEED_CLK_GATE_LCLK] =	{  8,  5, "lclk-gate",		NULL,	0 }, /* LPC */
+	[ASPEED_CLK_GATE_LCLK] =	{  8,  5, "lclk-gate",		NULL,	CLK_IS_CRITICAL }, /* LPC clock from host. No parent dependency */
 	[ASPEED_CLK_GATE_USBUHCICLK] =	{  9, 15, "usb-uhci-gate",	NULL,	0 }, /* USB1.1 (requires port 2 enabled) */
 	[ASPEED_CLK_GATE_D1CLK] =	{ 10, 13, "d1clk-gate",		NULL,	0 }, /* GFX CRT */
 	[ASPEED_CLK_GATE_YCLK] =	{ 13,  4, "yclk-gate",		NULL,	0 }, /* HAC */
@@ -103,7 +103,7 @@  static const struct aspeed_gate_data aspeed_gates[] = {
 	[ASPEED_CLK_GATE_UART1CLK] =	{ 15, -1, "uart1clk-gate",	"uart",	0 }, /* UART1 */
 	[ASPEED_CLK_GATE_UART2CLK] =	{ 16, -1, "uart2clk-gate",	"uart",	0 }, /* UART2 */
 	[ASPEED_CLK_GATE_UART5CLK] =	{ 17, -1, "uart5clk-gate",	"uart",	0 }, /* UART5 */
-	[ASPEED_CLK_GATE_ESPICLK] =	{ 19, -1, "espiclk-gate",	NULL,	0 }, /* eSPI */
+	[ASPEED_CLK_GATE_ESPICLK] =	{ 19, -1, "espiclk-gate",	NULL,	CLK_IS_CRITICAL }, /* eSPI clock from host. No parent dependency */
 	[ASPEED_CLK_GATE_MAC1CLK] =	{ 20, 11, "mac1clk-gate",	"mac",	0 }, /* MAC1 */
 	[ASPEED_CLK_GATE_MAC2CLK] =	{ 21, 12, "mac2clk-gate",	"mac",	0 }, /* MAC2 */
 	[ASPEED_CLK_GATE_RSACLK] =	{ 24, -1, "rsaclk-gate",	NULL,	0 }, /* RSA */