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@xxxxxxxxxxxxxx>
Reported-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
---
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
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