From: Jarkko Nikula <jarkko.nikula@linux.intel.com>
To: John Stultz <john.stultz@linaro.org>,
lkml <linux-kernel@vger.kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Wolfram Sang <wsa@kernel.org>,
linux-i2c@vger.kernel.org
Subject: Re: [PATCH] i2c: designware: Fix functionality in !CONFIG_ACPI case
Date: Tue, 23 Jun 2020 10:59:40 +0300 [thread overview]
Message-ID: <d6c317ee-4f97-9c57-6b04-1eabd814b6ce@linux.intel.com> (raw)
In-Reply-To: <20200623025144.34246-1-john.stultz@linaro.org>
Hi
On 6/23/20 5:51 AM, John Stultz wrote:
> On the HiKey board, where CONFIG_ACPI is not set, we started
> to see a graphics regression where the adv7511 HDMI bridge driver
> wasn't probing. This was due to the i2c bus failing to start up.
>
> I bisected the problem down to commit f9288fcc5c615 ("i2c:
> designware: Move ACPI parts into common module") and after
> looking at it a bit, I realized that change moved some
> initialization into i2c_dw_acpi_adjust_bus_speed(). However,
> i2c_dw_acpi_adjust_bus_speed() is only functional if CONFIG_ACPI
> is set.
>
> This patch pulls i2c_dw_acpi_adjust_bus_speed() out of the
> ifdef CONFIG_ACPI conditional, and gets the board working again.
>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>
> Cc: Wolfram Sang <wsa@kernel.org>
> Cc: linux-i2c@vger.kernel.org
> Fixes: f9288fcc5c615 ("i2c: designware: Move ACPI parts into common module")
> Signed-off-by: John Stultz <john.stultz@linaro.org>
> ---
> drivers/i2c/busses/i2c-designware-common.c | 4 ++--
> drivers/i2c/busses/i2c-designware-core.h | 3 +--
> 2 files changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
> index e3a8640db7da..33de185e15f2 100644
> --- a/drivers/i2c/busses/i2c-designware-common.c
> +++ b/drivers/i2c/busses/i2c-designware-common.c
> @@ -286,6 +286,8 @@ int i2c_dw_acpi_configure(struct device *device)
> }
> EXPORT_SYMBOL_GPL(i2c_dw_acpi_configure);
>
> +#endif /* CONFIG_ACPI */
> +
I think the regression is in these lines below that were moved from
probe to i2c_dw_acpi_adjust_bus_speed() and cause that neither
"cloock-frequency" device property or I2C_MAX_FAST_MODE_FREQ affect the
bus speed when CONFIG_ACPI is not set.
+ /*
+ * Find bus speed from the "clock-frequency" device property, ACPI
+ * or by using fast mode if neither is set.
+ */
+ if (acpi_speed && t->bus_freq_hz)
+ t->bus_freq_hz = min(t->bus_freq_hz, acpi_speed);
+ else if (acpi_speed || t->bus_freq_hz)
+ t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
+ else
+ t->bus_freq_hz = I2C_MAX_FAST_MODE_FREQ;
Andy: what you think should the i2c_dw_acpi_adjust_bus_speed() fixed to
return adjusted speed or zero if not found (also for !CONFIG_ACPI) and
move above lines back to probe? It looks more clear to me that way and
should fix the regression I think.
--
Jarkko
next prev parent reply other threads:[~2020-06-23 7:59 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-23 2:51 [PATCH] i2c: designware: Fix functionality in !CONFIG_ACPI case John Stultz
2020-06-23 7:59 ` Jarkko Nikula [this message]
2020-06-23 8:33 ` Jarkko Nikula
2020-06-23 8:45 ` Andy Shevchenko
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