RE: [PATCH 1/1] clk: aspeed: modify some default clks are critical

From: Ryan Chen
Date: Tue Sep 29 2020 - 04:37:41 EST

> From: Joel Stanley <joel@xxxxxxxxx>
> Sent: Tuesday, September 29, 2020 4:04 PM
> To: Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>; Jae Hyun Yoo
> <jae.hyun.yoo@xxxxxxxxxxxxxxx>; Andrew Jeffery <andrew@xxxxxxxx>
> Cc: Michael Turquette <mturquette@xxxxxxxxxxxx>; Stephen Boyd
> <sboyd@xxxxxxxxxx>; linux-clk@xxxxxxxxxxxxxxx; Linux ARM
> <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; linux-aspeed
> <linux-aspeed@xxxxxxxxxxxxxxxx>; Linux Kernel Mailing List
> <linux-kernel@xxxxxxxxxxxxxxx>; BMC-SW <BMC-SW@xxxxxxxxxxxxxx>
> Subject: Re: [PATCH 1/1] clk: aspeed: modify some default clks are critical
>
> On Mon, 28 Sep 2020 at 07:01, Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>
> wrote:
> >
> > In ASPEED SoC LCLK is LPC clock for all SuperIO device, UART1/UART2
> > are default for Host SuperIO UART device, eSPI clk for Host eSPI bus
> > access eSPI slave channel, those clks can't be disable should keep
> > default, otherwise will affect Host side access SuperIO and SPI slave device.
> >
> > Signed-off-by: Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>
> > ---
> > drivers/clk/clk-aspeed.c | 8 ++++---- drivers/clk/clk-ast2600.c | 8
> > ++++----
> > 2 files changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/clk/clk-aspeed.c b/drivers/clk/clk-aspeed.c index
> > 411ff5fb2c07..d348c4fd3f9f 100644
> > --- a/drivers/clk/clk-aspeed.c
> > +++ b/drivers/clk/clk-aspeed.c
> > @@ -54,15 +54,15 @@ 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 */
> > [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 */
> > [ASPEED_CLK_GATE_USBPORT1CLK] = { 14, 14, "usb-port1-gate",
> NULL, 0 }, /* USB2 hub/USB2 host port 1/USB1.1 dev */
> > - [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_UART1CLK] = { 15, -1, "uart1clk-gate",
> "uart", CLK_IS_CRITICAL }, /* UART1 */
> > + [ASPEED_CLK_GATE_UART2CLK] = { 16, -1, "uart2clk-gate",
> "uart", CLK_IS_CRITICAL }, /* 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 */
>
> This is fine for systems that have eSPI. For systems that do not use eSPI, the
> clocks are not "required".
>
> I was sent a similar patch by Jae some time ago:
>
>
> https://lore.kernel.org/openbmc/697a184b-ef99-a46e-bf98-4d339b3aafd8@lin
> ux.intel.com/
>
> Better is to associate drivers with these clocks, and those drivers will ensure
> they are left enabled.
>
> Alternatively, we will need to come up with a device tree binding to describe
> the hardware requirement that these clocks are left on.
>
ASPEED BMC SoC have SuperIO device that default enable, even without BMC fw boot.
Host can use SUART1/SUART2/GPIO....
That the reason even Linux kernel boot should not change the SoC default clk, that is the impact.

Ryan
>
> > [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 */
> > diff --git a/drivers/clk/clk-ast2600.c b/drivers/clk/clk-ast2600.c
> > index bbacaccad554..6802a2d5bbe2 100644
> > --- a/drivers/clk/clk-ast2600.c
> > +++ b/drivers/clk/clk-ast2600.c
> > @@ -86,8 +86,8 @@ static const struct aspeed_gate_data aspeed_g6_gates[]
> = {
> > /* Reserved 26 */
> > [ASPEED_CLK_GATE_EMMCCLK] = { 27, 16,
> "emmcclk-gate", NULL, 0 }, /* For card clk */
> > /* Reserved 28/29/30 */
> > - [ASPEED_CLK_GATE_LCLK] = { 32, 32, "lclk-gate",
> NULL, 0 }, /* LPC */
> > - [ASPEED_CLK_GATE_ESPICLK] = { 33, -1, "espiclk-gate",
> NULL, 0 }, /* eSPI */
> > + [ASPEED_CLK_GATE_LCLK] = { 32, 32, "lclk-gate",
> NULL, CLK_IS_CRITICAL }, /* LPC */
> > + [ASPEED_CLK_GATE_ESPICLK] = { 33, -1, "espiclk-gate",
> NULL, CLK_IS_CRITICAL }, /* eSPI */
> > [ASPEED_CLK_GATE_REF1CLK] = { 34, -1, "ref1clk-gate",
> "clkin", CLK_IS_CRITICAL },
> > /* Reserved 35 */
> > [ASPEED_CLK_GATE_SDCLK] = { 36, 56, "sdclk-gate",
> NULL, 0 }, /* SDIO/SD */
> > @@ -102,8 +102,8 @@ static const struct aspeed_gate_data
> aspeed_g6_gates[] = {
> > [ASPEED_CLK_GATE_I3C5CLK] = { 45, 45, "i3c5clk-gate",
> NULL, 0 }, /* I3C5 */
> > [ASPEED_CLK_GATE_I3C6CLK] = { 46, 46, "i3c6clk-gate",
> NULL, 0 }, /* I3C6 */
> > [ASPEED_CLK_GATE_I3C7CLK] = { 47, 47, "i3c7clk-gate",
> NULL, 0 }, /* I3C7 */
> > - [ASPEED_CLK_GATE_UART1CLK] = { 48, -1, "uart1clk-gate",
> "uart", 0 }, /* UART1 */
> > - [ASPEED_CLK_GATE_UART2CLK] = { 49, -1, "uart2clk-gate",
> "uart", 0 }, /* UART2 */
> > + [ASPEED_CLK_GATE_UART1CLK] = { 48, -1, "uart1clk-gate",
> "uart", CLK_IS_CRITICAL }, /* UART1 */
> > + [ASPEED_CLK_GATE_UART2CLK] = { 49, -1, "uart2clk-gate",
> "uart", CLK_IS_CRITICAL }, /* UART2 */
> > [ASPEED_CLK_GATE_UART3CLK] = { 50, -1,
> "uart3clk-gate", "uart", 0 }, /* UART3 */
> > [ASPEED_CLK_GATE_UART4CLK] = { 51, -1,
> "uart4clk-gate", "uart", 0 }, /* UART4 */
> > [ASPEED_CLK_GATE_MAC3CLK] = { 52, 52,
> "mac3clk-gate", "mac34", 0 }, /* MAC3 */
> > --
> > 2.17.1
> >