Re: [PATCH V5 2/7] soc: qcom-geni-se: Add interconnect support to fix earlycon crash
From: Matthias Kaehlcke <mka@chromium.org>
Date: 2020-05-08 17:59:44
Also in:
linux-arm-msm, linux-i2c, linux-serial, linux-spi
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:
quoted hunk ↗ jump to hunk
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 <redacted> 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.
+ 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.
+ }
+ }
+ 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).
quoted hunk ↗ jump to hunk
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:
if (!console_drivers)
goto exit;
+ 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?