Re: [Qemu-devel] [PATCH 1/5] pci: introduce PC_PCI_CONFIG_ENABLED()

[Marcel Apfelbaum <marcel.apfelbaum@gmail.com>]

Hi,

On Tue, 2014-11-04 at 17:12 +0800, Hu Tao wrote:
> This makes code more readable.
> 
> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
> ---
>  hw/mips/gt64xxx_pci.c | 4 ++--
>  hw/pci/pci_host.c     | 5 +++--
>  include/hw/pci/pci.h  | 2 ++
>  3 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/mips/gt64xxx_pci.c b/hw/mips/gt64xxx_pci.c
> index 1f2fe5f..a49dbd7 100644
> --- a/hw/mips/gt64xxx_pci.c
> +++ b/hw/mips/gt64xxx_pci.c
> @@ -564,7 +564,7 @@ static void gt64120_writel (void *opaque, hwaddr addr,
>          if (!(s->regs[GT_PCI0_CMD] & 1) && (phb->config_reg & 0x00fff800)) {
>              val = bswap32(val);
>          }
> -        if (phb->config_reg & (1u << 31)) {
> +        if (PC_PCI_CONFIG_ENABLED(phb->config_reg)) 
I really like readable MACROS instead of magic numbers,
however I have 3 suggestions:
1. PC_PCI_CONFIG_ENABLED is still not really clear, because
of the "PC" prefix that is too wide in my IMHO (maybe PCI_HOST_BRIDGE_CONFIG_ENABLED)
when this macro refers only to host bridges.  
2. Maybe go the "extra mile" and let the macro receive
a host bridge as parameter PCI_HOST_BRIDGE_CONFIG_ENABLED(host_bridge).
3. Maybe make it an inline function? Just wondering
 
>              pci_data_write(phb->bus, phb->config_reg, val, 4);
>          }
>          break;
> @@ -804,7 +804,7 @@ static uint64_t gt64120_readl (void *opaque,
>          val = phb->config_reg;
>          break;
>      case GT_PCI0_CFGDATA:
> -        if (!(phb->config_reg & (1 << 31))) {
> +        if (!PC_PCI_CONFIG_ENABLED(phb->config_reg)) {
>              val = 0xffffffff;
>          } else {
>              val = pci_data_read(phb->bus, phb->config_reg, 4);
> diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
> index 3e26f92..f2a69ea 100644
> --- a/hw/pci/pci_host.c
> +++ b/hw/pci/pci_host.c
> @@ -133,8 +133,9 @@ static void pci_host_data_write(void *opaque, hwaddr addr,
>      PCIHostState *s = opaque;
>      PCI_DPRINTF("write addr " TARGET_FMT_plx " len %d val %x\n",
>                  addr, len, (unsigned)val);
> -    if (s->config_reg & (1u << 31))
> +    if (PC_PCI_CONFIG_ENABLED(s->config_reg)) {
>          pci_data_write(s->bus, s->config_reg | (addr & 3), val, len);
> +    }
>  }
>  
>  static uint64_t pci_host_data_read(void *opaque,
> @@ -142,7 +143,7 @@ static uint64_t pci_host_data_read(void *opaque,
>  {
>      PCIHostState *s = opaque;
>      uint32_t val;
> -    if (!(s->config_reg & (1U << 31))) {
> +    if (!PC_PCI_CONFIG_ENABLED(s->config_reg)) {
>          return 0xffffffff;
>      }
>      val = pci_data_read(s->bus, s->config_reg | (addr & 3), len);
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index c352c7b..3d42d7f 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -13,6 +13,8 @@
>  
>  #include "hw/pci/pcie.h"
>  
> +#define PC_PCI_CONFIG_ENABLED(addr) (addr & (1U << 31))
Again, maybe move this to "hw/pci/pci_host" since is specific to host bridges?

Thanks,
Marcel
> +
>  /* PCI bus */
>  
>  #define PCI_DEVFN(slot, func)   ((((slot) & 0x1f) << 3) | ((func) & 0x07))