From: Faiz Abbas
> Sent: 19 October 2017 14:09
> On Thursday 19 October 2017 06:13 PM, Faiz Abbas wrote:
> > Enable support for printing the LTSSM link state for debugging PCI
> > when link is down.
> >
> > Signed-off-by: Faiz Abbas <faiz_abbas@xxxxxx>
> > ---
> > v2:
> > 1. Changed dev_err() to dev_dbg()
> > 2. Changed static char array to static const char * const
> > 3. format changes
> >
> > drivers/pci/dwc/pci-dra7xx.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 48 insertions(+)
> >
> > diff --git a/drivers/pci/dwc/pci-dra7xx.c b/drivers/pci/dwc/pci-dra7xx.c
> > index 34427a6..0e70e77 100644
> > --- a/drivers/pci/dwc/pci-dra7xx.c
> > +++ b/drivers/pci/dwc/pci-dra7xx.c
> > @@ -98,6 +98,45 @@ struct dra7xx_pcie_of_data {
> >
> > #define to_dra7xx_pcie(x) dev_get_drvdata((x)->dev)
> >
> > +static const char * const state[] = {
> > + "DETECT_QUIET",
...
> > + "RCVRY_EQ3"
> > +};
> > +
> > static inline u32 dra7xx_pcie_readl(struct dra7xx_pcie *pcie, u32 offset)
> > {
> > return readl(pcie->base + offset);
> > @@ -118,6 +157,15 @@ static int dra7xx_pcie_link_up(struct dw_pcie *pci)
> > {
> > struct dra7xx_pcie *dra7xx = to_dra7xx_pcie(pci);
> > u32 reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_PHY_CS);
> > + u32 cmd_reg;
> > + u32 ltssm_state;
> > +
> > + if (!(reg & LINK_UP)) {
> > + cmd_reg = dra7xx_pcie_readl(dra7xx,
> > + PCIECTRL_DRA7XX_CONF_DEVICE_CMD);
> > + ltssm_state = (cmd_reg & GENMASK(7, 2)) >> 2;
> > + dev_dbg(pci->dev, "Link state:%s\n", state[ltssm_state]);
Hmmm... GENMASK leaves by hunting header files...
Why not (cmd_reg >> 2) & 63 and explicitly define state[64]
to guarantee that you never print anything worse than a NULL
pointer.
> > + }
> >
> > return !!(reg & LINK_UP);
> > }
> >
>
> I missed David's comment in v1. Will submit a new version. Please ignore.
I've a 'neat' trick for generating strings that match constants.
You can get the compiler to do all the work for you:
(Assuming I've typed it correctly)
#define LTSSM_DEFS(x) \
x(DETECT_QUIET) \
x(DETECT_ACT) \
(continue for all the names)
Define an enum with the named constants:
#define X(name) LTSSM_STATE_##name,
enum (LTSSM_DEFS(X) LTSSM_STATE_SIZE=64);
#undef X
Array of strings:
#define X(name) [LTSSM_STATE_##name] = #name
static const char * const state_names[LTSSM_STATE_SIZE] = { LTSSM_DEFS(X) };
#undef X
David
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