| Message ID | 20210120020116.576669-1-marex@denx.de (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] net: dsa: microchip: Adjust reset release timing to match reference reset circuit | expand |
| Context | Check | Description |
|---|---|---|
| netdev/cover_letter | success | Link |
| netdev/fixes_present | success | Link |
| netdev/patch_count | success | Link |
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/subject_prefix | success | Link |
| netdev/cc_maintainers | warning | 5 maintainers not CCed: olteanv@gmail.com vivien.didelot@gmail.com davem@davemloft.net woojung.huh@microchip.com UNGLinuxDriver@microchip.com |
| netdev/source_inline | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Link |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/verify_fixes | success | Link |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 8 lines checked |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/header_inline | success | Link |
| netdev/stable | success | Stable not CCed |
On 1/19/2021 6:01 PM, Marek Vasut wrote: > KSZ8794CNX datasheet section 8.0 RESET CIRCUIT describes recommended > circuit for interfacing with CPU/FPGA reset consisting of 10k pullup > resistor and 10uF capacitor to ground. This circuit takes ~100 mS to > rise enough to release the reset. > > For maximum supply voltage VDDIO=3.3V VIH=2.0V R=10kR C=10uF that is > VDDIO - VIH > t = R * C * -ln( ------------- ) = 10000*0.00001*-(-0.93)=0.093 S > VDDIO > so we need ~95 mS for the reset to really de-assert, and then the > original 100uS for the switch itself to come out of reset. Simply > msleep() for 100 mS which fits the constraint with a bit of extra > space. This is nitpicking but the unit symbol for seconds is 's', not 'S' which is for Siemens. With that fixed: Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
diff --git a/drivers/net/dsa/microchip/ksz_common.c b/drivers/net/dsa/microchip/ksz_common.c index 489963664443..389abfd27770 100644 --- a/drivers/net/dsa/microchip/ksz_common.c +++ b/drivers/net/dsa/microchip/ksz_common.c @@ -400,7 +400,7 @@ int ksz_switch_register(struct ksz_device *dev, gpiod_set_value_cansleep(dev->reset_gpio, 1); usleep_range(10000, 12000); gpiod_set_value_cansleep(dev->reset_gpio, 0); - usleep_range(100, 1000); + msleep(100); } mutex_init(&dev->dev_mutex);
KSZ8794CNX datasheet section 8.0 RESET CIRCUIT describes recommended circuit for interfacing with CPU/FPGA reset consisting of 10k pullup resistor and 10uF capacitor to ground. This circuit takes ~100 mS to rise enough to release the reset. For maximum supply voltage VDDIO=3.3V VIH=2.0V R=10kR C=10uF that is VDDIO - VIH t = R * C * -ln( ------------- ) = 10000*0.00001*-(-0.93)=0.093 S VDDIO so we need ~95 mS for the reset to really de-assert, and then the original 100uS for the switch itself to come out of reset. Simply msleep() for 100 mS which fits the constraint with a bit of extra space. Fixes: 5b797980908a ("net: dsa: microchip: Implement recommended reset timing") Signed-off-by: Marek Vasut <marex@denx.de> Cc: Andrew Lunn <andrew@lunn.ch> Cc: Florian Fainelli <f.fainelli@gmail.com> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Michael Grzeschik <m.grzeschik@pengutronix.de> Cc: Paul Barker <pbarker@konsulko.com> --- drivers/net/dsa/microchip/ksz_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)