From: Akash Asthana <akashast@codeaurora.org>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: gregkh@linuxfoundation.org, agross@kernel.org,
bjorn.andersson@linaro.org, wsa@the-dreams.de,
broonie@kernel.org, mark.rutland@arm.com, robh+dt@kernel.org,
linux-i2c@vger.kernel.org, linux-spi@vger.kernel.org,
devicetree@vger.kernel.org, swboyd@chromium.org,
mgautam@codeaurora.org, linux-arm-msm@vger.kernel.org,
linux-serial@vger.kernel.org, dianders@chromium.org,
evgreen@chromium.org, georgi.djakov@linaro.org
Subject: Re: [PATCH V5 2/7] soc: qcom-geni-se: Add interconnect support to fix earlycon crash
Date: Thu, 14 May 2020 12:15:44 +0530 [thread overview]
Message-ID: <294b33e5-cf5a-8abc-2152-afa01664d962@codeaurora.org> (raw)
In-Reply-To: <20200508175938.GB4525@google.com>
Hi Matthias,
On 5/8/2020 11:29 PM, Matthias Kaehlcke wrote:
> Hi Akash,
>
> overall this looks good to me, a few comments inline
>
> On Fri, May 08, 2020 at 12:03:34PM +0530, Akash Asthana wrote:
>> QUP core clock is shared among all the SE drivers present on particular
>> QUP wrapper, the system will reset(unclocked access) if earlycon used after
>> QUP core clock is put to 0 from other SE drivers before real console comes
>> up.
>>
>> As earlycon can't vote for it's QUP core need, to fix this add ICC
>> support to common/QUP wrapper driver and put vote for QUP core from
>> probe on behalf of earlycon and remove vote during earlycon exit call.
>>
>> Signed-off-by: Akash Asthana <akashast@codeaurora.org>
>> Reported-by: Matthias Kaehlcke <mka@chromium.org>
>> ---
>> Change in V3:
>> - Add geni_remove_earlycon_icc_vote API that will be used by earlycon
>> exit function to remove ICC vote for earlyconsole.
>> - Remove suspend/resume hook for geni-se driver as we are no longer
>> removing earlyconsole ICC vote from system suspend, we are removing
>> from earlycon exit.
>>
>> Change in V4:
>> - As per Matthias comment make 'earlycon_wrapper' as static structure.
>>
>> Changes in V5:
>> - Vote for core path only after checking whether "qcom_geni" earlycon is
>> actually present or not by traversing over structure "console_drivers".
>>
>> drivers/soc/qcom/qcom-geni-se.c | 63 +++++++++++++++++++++++++++++++++++
>> drivers/tty/serial/qcom_geni_serial.c | 7 ++++
>> include/linux/qcom-geni-se.h | 2 ++
>> 3 files changed, 72 insertions(+)
>>
>> diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
>> index 63403bf..66fe6f2 100644
>> --- a/drivers/soc/qcom/qcom-geni-se.c
>> +++ b/drivers/soc/qcom/qcom-geni-se.c
>> @@ -3,6 +3,7 @@
>>
>> #include <linux/acpi.h>
>> #include <linux/clk.h>
>> +#include <linux/console.h>
>> #include <linux/slab.h>
>> #include <linux/dma-mapping.h>
>> #include <linux/io.h>
>> @@ -90,11 +91,14 @@ struct geni_wrapper {
>> struct device *dev;
>> void __iomem *base;
>> struct clk_bulk_data ahb_clks[NUM_AHB_CLKS];
>> + struct geni_icc_path to_core;
>> };
>>
>> static const char * const icc_path_names[] = {"qup-core", "qup-config",
>> "qup-memory"};
>>
>> +static struct geni_wrapper *earlycon_wrapper;
>> +
>> #define QUP_HW_VER_REG 0x4
>>
>> /* Common SE registers */
>> @@ -812,11 +816,33 @@ int geni_icc_disable(struct geni_se *se)
>> }
>> EXPORT_SYMBOL(geni_icc_disable);
>>
>> +void geni_remove_earlycon_icc_vote(void)
>> +{
>> + struct geni_wrapper *wrapper = earlycon_wrapper;
>> + struct device_node *parent = of_get_next_parent(wrapper->dev->of_node);
> Do we need to check that earlycon_wrapper != NULL before dereferencing it?
> In theory this should not happen, but better be safe.
Ok, I will add NULL check.
>
>> + struct device_node *child;
>> +
>> + for_each_child_of_node(parent, child) {
>> + if (of_device_is_compatible(child, "qcom,geni-se-qup")) {
>> + wrapper = platform_get_drvdata(of_find_device_by_node(
>> + child));
>> + icc_put(wrapper->to_core.path);
>> + wrapper->to_core.path = NULL;
> nit: setting the path to NULL isn't really needed IIUC.
icc_put just free the path and don't reinitialize the path to NULL, if
the path is used after it is put target will crash. So just for safety I
am setting this path to NULL.
>
>> + }
>> + }
>> + of_node_put(parent);
>> +
>> + earlycon_wrapper = NULL;
>> +}
>> +EXPORT_SYMBOL(geni_remove_earlycon_icc_vote);
>> +
>> static int geni_se_probe(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> struct resource *res;
>> struct geni_wrapper *wrapper;
>> + struct console *bcon;
>> + int earlycon_present = 0;
> use bool & true/false
>
> The variable is only used when CONFIG_SERIAL_EARLYCON is set, I think
> you need to add '__maybe_unused' to avoid a compiler warning then earlycon
> support is disabled.
>
> bikeshed: 'has_earlycon' would be slightly more concise (feel free to ignore).
Ok
>
>> int ret;
>>
>> wrapper = devm_kzalloc(dev, sizeof(*wrapper), GFP_KERNEL);
>> @@ -839,6 +865,43 @@ static int geni_se_probe(struct platform_device *pdev)
>> }
>> }
>>
>> +#ifdef CONFIG_SERIAL_EARLYCON
>> + if (console_drivers)
> The loop should have curly braces ("use braces when a loop contains more than
> a single simple statement"), even though the compiler doesn't need them in
> this case. This is not a loop, but I was told by a maintainer that it equally
> applies, which makes sense.
>
> You could avoid one level of indentation through:
Ok
>
> if (!console_drivers)
> goto exit;
I think I can omit this extra check because "for_each_console" will take
care of this.
>
>> + for_each_console(bcon)
> ditto (braces)
>
>> + if (!strcmp(bcon->name, "qcom_geni")) {
>> + earlycon_present = 1;
>> + break;
>> + }
>> + if (!earlycon_present)
>> + goto exit;
>> +
>> + wrapper->to_core.path = devm_of_icc_get(dev, "qup-core");
>> + if (IS_ERR(wrapper->to_core.path))
>> + return PTR_ERR(wrapper->to_core.path);
>> + /*
>> + * Put minmal BW request on core clocks on behalf of early console.
>> + * The vote will be removed earlycon exit function.
>> + *
>> + * Note: We are putting vote on each QUP wrapper instead only to which
>> + * earlycon is connected because QUP core clock of different wrapper
>> + * share same voltage domain. If core1 is put to 0, then core2 will
>> + * also run at 0, if not voted. Default ICC vote will be removed ASA
>> + * we touch any of the core clock.
>> + * core1 = core2 = max(core1, core2)
>> + */
>> + ret = icc_set_bw(wrapper->to_core.path, GENI_DEFAULT_BW,
>> + GENI_DEFAULT_BW);
> nit: the indentation is a bit odd. Align with 'wrapper->to_core.path' or a
> nearby tab stop?
ok
Thanks for providing the feedback.
Regards,
Akash
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project
next prev parent reply other threads:[~2020-05-14 6:46 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-08 6:33 [PATCH V5 0/7] Add interconnect support to QSPI and QUP drivers Akash Asthana
2020-05-08 6:33 ` [PATCH V5 1/7] soc: qcom: geni: Support for ICC voting Akash Asthana
2020-05-08 17:13 ` Matthias Kaehlcke
2020-05-12 14:02 ` Akash Asthana
2020-05-08 19:03 ` Matthias Kaehlcke
2020-05-12 14:26 ` Akash Asthana
2020-05-08 6:33 ` [PATCH V5 2/7] soc: qcom-geni-se: Add interconnect support to fix earlycon crash Akash Asthana
2020-05-08 17:59 ` Matthias Kaehlcke
2020-05-08 19:14 ` Matthias Kaehlcke
2020-05-14 7:03 ` Akash Asthana
2020-05-14 6:45 ` Akash Asthana [this message]
2020-05-09 12:11 ` Andy Shevchenko
2020-05-14 7:34 ` Akash Asthana
2020-05-08 6:33 ` [PATCH V5 3/7] i2c: i2c-qcom-geni: Add interconnect support Akash Asthana
2020-05-08 18:16 ` Matthias Kaehlcke
2020-05-15 10:03 ` Wolfram Sang
2020-05-08 6:33 ` [PATCH V5 4/7] spi: spi-geni-qcom: " Akash Asthana
2020-05-08 10:16 ` Mark Brown
2020-05-08 18:25 ` Matthias Kaehlcke
2020-05-14 7:37 ` Akash Asthana
2020-05-08 6:33 ` [PATCH V5 5/7] tty: serial: qcom_geni_serial: " Akash Asthana
2020-05-08 18:38 ` Matthias Kaehlcke
2020-05-08 6:33 ` [PATCH V5 6/7] spi: spi-qcom-qspi: " Akash Asthana
2020-05-08 10:16 ` Mark Brown
2020-05-08 18:53 ` Matthias Kaehlcke
2020-05-18 13:10 ` Akash Asthana
2020-05-08 6:33 ` [PATCH V5 7/7] arm64: dts: sc7180: Add interconnect for QUP and QSPI Akash Asthana
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