[PATCH] staging: mt7621-pci: simplify 'mt7621_pcie_init_virtual_bridges' function
NeilBrown
neil at brown.name
Sat Apr 11 03:26:11 UTC 2020
On Sun, Mar 08 2020, Sergio Paracuellos wrote:
> Function 'mt7621_pcie_init_virtual_bridges' is a bit mess and can be
> refactorized properly in a cleaner way. Introduce new 'pcie_rmw' inline
> function helper to do clear and set the correct bits this function needs
> to work.
>
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos at gmail.com>
> ---
> Changes are only compile tested.
> drivers/staging/mt7621-pci/pci-mt7621.c | 85 ++++++++++---------------
> 1 file changed, 33 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/staging/mt7621-pci/pci-mt7621.c b/drivers/staging/mt7621-pci/pci-mt7621.c
> index 3633c924848e..1f860c5ef588 100644
> --- a/drivers/staging/mt7621-pci/pci-mt7621.c
> +++ b/drivers/staging/mt7621-pci/pci-mt7621.c
> @@ -57,13 +57,13 @@
> #define RALINK_PCI_IOBASE 0x002C
>
> /* PCICFG virtual bridges */
> -#define MT7621_BR0_MASK GENMASK(19, 16)
> -#define MT7621_BR1_MASK GENMASK(23, 20)
> -#define MT7621_BR2_MASK GENMASK(27, 24)
> -#define MT7621_BR_ALL_MASK GENMASK(27, 16)
> -#define MT7621_BR0_SHIFT 16
> -#define MT7621_BR1_SHIFT 20
> -#define MT7621_BR2_SHIFT 24
> +#define PCIE_P2P_MAX 3
This is one of my bug-bears. The number "3" here is not a MAXimum.
It is a count or a number. It is how many masks there are.
The masks are numbered 0, 1, 2 so the maximum is 2.
I would rename this PCI_P2P_CNT.
> +#define PCIE_P2P_BR_DEVNUM_SHIFT(p) (16 + (p) * 4)
> +#define PCIE_P2P_BR_DEVNUM0_SHIFT PCIE_P2P_BR_DEVNUM_SHIFT(0)
> +#define PCIE_P2P_BR_DEVNUM1_SHIFT PCIE_P2P_BR_DEVNUM_SHIFT(1)
> +#define PCIE_P2P_BR_DEVNUM2_SHIFT PCIE_P2P_BR_DEVNUM_SHIFT(2)
> +#define PCIE_P2P_BR_DEVNUM_MASK 0xf
> +#define PCIE_P2P_BR_DEVNUM_MASK_FULL (0xfff << PCIE_P2P_BR_DEVNUM0_SHIFT)
>
> /* PCIe RC control registers */
> #define MT7621_PCIE_OFFSET 0x2000
> @@ -154,6 +154,15 @@ static inline void pcie_write(struct mt7621_pcie *pcie, u32 val, u32 reg)
> writel(val, pcie->base + reg);
> }
>
> +static inline void pcie_rmw(struct mt7621_pcie *pcie, u32 reg, u32 clr, u32 set)
> +{
> + u32 val = readl(pcie->base + reg);
> +
> + val &= ~clr;
> + val |= set;
> + writel(val, pcie->base + reg);
> +}
> +
> static inline u32 pcie_port_read(struct mt7621_pcie_port *port, u32 reg)
> {
> return readl(port->base + reg);
> @@ -554,7 +563,9 @@ static void mt7621_pcie_enable_ports(struct mt7621_pcie *pcie)
> static int mt7621_pcie_init_virtual_bridges(struct mt7621_pcie *pcie)
> {
> u32 pcie_link_status = 0;
> - u32 val = 0;
> + u32 n;
> + int i;
> + u32 p2p_br_devnum[PCIE_P2P_MAX];
> struct mt7621_pcie_port *port;
>
> list_for_each_entry(port, &pcie->ports, list) {
> @@ -567,50 +578,20 @@ static int mt7621_pcie_init_virtual_bridges(struct mt7621_pcie *pcie)
> if (pcie_link_status == 0)
> return -1;
>
> - /*
> - * pcie(2/1/0) link status pcie2_num pcie1_num pcie0_num
> - * 3'b000 x x x
> - * 3'b001 x x 0
> - * 3'b010 x 0 x
> - * 3'b011 x 1 0
> - * 3'b100 0 x x
> - * 3'b101 1 x 0
> - * 3'b110 1 0 x
> - * 3'b111 2 1 0
> - */
> - switch (pcie_link_status) {
> - case 2:
> - val = pcie_read(pcie, RALINK_PCI_PCICFG_ADDR);
> - val &= ~(MT7621_BR0_MASK | MT7621_BR1_MASK);
> - val |= 0x1 << MT7621_BR0_SHIFT;
> - val |= 0x0 << MT7621_BR1_SHIFT;
> - pcie_write(pcie, val, RALINK_PCI_PCICFG_ADDR);
> - break;
> - case 4:
> - val = pcie_read(pcie, RALINK_PCI_PCICFG_ADDR);
> - val &= ~MT7621_BR_ALL_MASK;
> - val |= 0x1 << MT7621_BR0_SHIFT;
> - val |= 0x2 << MT7621_BR1_SHIFT;
> - val |= 0x0 << MT7621_BR2_SHIFT;
> - pcie_write(pcie, val, RALINK_PCI_PCICFG_ADDR);
> - break;
> - case 5:
> - val = pcie_read(pcie, RALINK_PCI_PCICFG_ADDR);
> - val &= ~MT7621_BR_ALL_MASK;
> - val |= 0x0 << MT7621_BR0_SHIFT;
> - val |= 0x2 << MT7621_BR1_SHIFT;
> - val |= 0x1 << MT7621_BR2_SHIFT;
> - pcie_write(pcie, val, RALINK_PCI_PCICFG_ADDR);
> - break;
> - case 6:
> - val = pcie_read(pcie, RALINK_PCI_PCICFG_ADDR);
> - val &= ~MT7621_BR_ALL_MASK;
> - val |= 0x2 << MT7621_BR0_SHIFT;
> - val |= 0x0 << MT7621_BR1_SHIFT;
> - val |= 0x1 << MT7621_BR2_SHIFT;
> - pcie_write(pcie, val, RALINK_PCI_PCICFG_ADDR);
> - break;
> - }
> + n = 0;
> + for (i = 0; i < PCIE_P2P_MAX; i++)
Here, for example, 'i' never reaches the MAX value. Surely that is wrong.
> + if (pcie_link_status & BIT(i))
> + p2p_br_devnum[i] = n++;
> +
> + for (i = 0; i < PCIE_P2P_MAX; i++)
> + if ((pcie_link_status & BIT(i)) == 0)
> + p2p_br_devnum[i] = n++;
This second for loop seems like a change in functionality to what we had
before. Is that correct? I seems to make sense but as you didn't flag
the change in the commit message I thought I would ask.
Also I feel it would help to have a comment explaining what was going
on. There was a big comment here before. It wasn't particularly
helpful, but it was a little better than nothing.
Maybe:
/* Assign device numbers from zero to the enabled ports, then assigning
* remaining device numbers to any disabled ports
*/
Thanks,
NeilBrown
> +
> + pcie_rmw(pcie, RALINK_PCI_CONFIG_ADDR,
> + PCIE_P2P_BR_DEVNUM_MASK_FULL,
> + (p2p_br_devnum[0] << PCIE_P2P_BR_DEVNUM0_SHIFT) |
> + (p2p_br_devnum[1] << PCIE_P2P_BR_DEVNUM1_SHIFT) |
> + (p2p_br_devnum[2] << PCIE_P2P_BR_DEVNUM2_SHIFT));
>
> return 0;
> }
> --
> 2.19.1
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