Messages in this thread | | | Subject | Re: [PATCH v2 3/4] watchdog: iTCO_wdt: Fix PMC GCR memory mapping failure | From | sathyanarayanan kuppuswamy <> | Date | Fri, 17 Mar 2017 11:39:59 -0700 |
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On 03/17/2017 10:50 AM, Guenter Roeck wrote: > On Fri, Mar 17, 2017 at 10:24:35AM -0700, sathyanarayanan kuppuswamy wrote: >> >> On 03/17/2017 06:40 AM, Guenter Roeck wrote: >>> On 03/17/2017 04:43 AM, Rajneesh Bhardwaj wrote: >>>> On Thu, Mar 16, 2017 at 05:41:35PM -0700, Kuppuswamy Sathyanarayanan >>>> wrote: >>>>> Currently, iTCO watchdog driver uses memory map to access >>>>> PMC_CFG GCR register. But the entire GCR address space is >>>>> already mapped in intel_scu_ipc driver. So remapping the >>>> intel_pmc_ipc driver. >>>> >>>>> GCR register in this driver causes the mem request failure in >>>>> iTCO_wdt probe function. This patch fixes this issue by >>>>> using PMC GCR read/write API's to access PMC_CFG register. >>>>> >>>>> Signed-off-by: Kuppuswamy Sathyanarayanan >>>>> <sathyanarayanan.kuppuswamy@linux.intel.com> >>>>> --- >>>>> drivers/watchdog/iTCO_wdt.c | 31 +++++++------------------------ >>>>> 1 file changed, 7 insertions(+), 24 deletions(-) >>>>> >>>>> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c >>>>> index 3d0abc0..31abfc5 100644 >>>>> --- a/drivers/watchdog/iTCO_wdt.c >>>>> +++ b/drivers/watchdog/iTCO_wdt.c >>>>> @@ -68,6 +68,8 @@ >>>>> #include <linux/io.h> /* For inb/outb/... */ >>>>> #include <linux/platform_data/itco_wdt.h> >>>>> >>>>> +#include <asm/intel_pmc_ipc.h> >>>>> + >>>>> #include "iTCO_vendor.h" >>>>> >>>>> /* Address definitions for the TCO */ >>>>> @@ -94,12 +96,6 @@ struct iTCO_wdt_private { >>>>> unsigned int iTCO_version; >>>>> struct resource *tco_res; >>>>> struct resource *smi_res; >>>>> - /* >>>>> - * NO_REBOOT flag is Memory-Mapped GCS register bit 5 (TCO >>>>> version 2), >>>>> - * or memory-mapped PMC register bit 4 (TCO version 3). >>>>> - */ >>>> Better to retain this comment elsewhere. >>>> >>>>> - struct resource *gcs_pmc_res; >>>>> - unsigned long __iomem *gcs_pmc; >>>>> /* the lock for io operations */ >>>>> spinlock_t io_lock; >>>>> /* the PCI-device */ >>>>> @@ -176,9 +172,9 @@ static void iTCO_wdt_set_NO_REBOOT_bit(struct >>>>> iTCO_wdt_private *p) >>>>> >>>>> /* Set the NO_REBOOT bit: this disables reboots */ >>>>> if (p->iTCO_version >= 2) { >>>>> - val32 = readl(p->gcs_pmc); >>>>> + val32 = intel_pmc_gcr_read(PMC_GCR_PMC_CFG_REG); >>>> better to have protection and error handling, discussed in v2, 2/4. >>>> >>>> compiled and tested this on APL and i see iTCO_WDT driver loads fine. >>>> Since >>>> it impacts core WDT functionality, need to be thoroughly tested on >>>> various >>>> platforms. >>>> >>> I don't think I (or the watchdog mailing list) was copied on the original >>> patch. >> Sorry. Its my mistake. I will fix it in next series update. >>> Major immediate concern is that this introduces a dependency on external >>> code. >>> The pmc_ipc driver's Kconfig entry states "This is not needed for PC-type >>> machines". I don't know where the function is introduced, but I hope this >>> change >>> does not require the pmc_ipc code to be present on such machines for the >>> watchdog >>> to work. It would be bad if it does. If it doesn't, it appears that the >>> function >>> should not be declared in asm/intel_pmc_ipc.h. >> It should not create any compile time dependency with INTEL_PMC_IPC config >> option. If INTEL_PMC_IPC_CONFIG is disabled, we use >> empty definitions for these calls defined in asm/intel_pmc_ipc.h >> > So the watchdog driver would get an error if CONFIG_INTEL_PMC_IPC > is not defined ? And that is supposed to be acceptable ? Sorry, It looks like I missed your point in your previous email. I thought that gcs_pmc mem resource will be used only if watchdog device is enumerated by intel_pmc_ipc.c
After reviewing the code again, I found out this iTCO_wdt driver can also be enumerated by drivers/mfd/lpc_ich.c and drivers/i2c/busses/i2c-i801.c. Both these drivers pass the GCS as memory resource. So using intel_pmc_ipc specific calls will break watchdog functionality if its enumerated by any device other than intel_pmic_ipc.c
May be I should add a flag for ipc case in itco_wdt_platform_data and handle this as a special case. > >> But iTCO_wdt driver already has runtime dependency with INTEL_PMIC_IPC if >> its version iTCO_version >= 2. >> > Unless I am missing something, there is no explicit dependency. AFAICS > the watchdog driver works just fine if INTEL_PMIC_IPC is not enabled, > and/or if it is built as module and the module is not loaded. > > Maybe you mean that the watchdog driver doesn't load if the INTEL_PMIC_IPC > driver is loaded. That would be a bug, not a dependency. > > Guenter >
-- Sathyanarayanan Kuppuswamy Android kernel developer
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