[V3,4/6] PCI: rcar: Replace (8 * n) with (n << 3)
diff mbox series

Message ID 20190323015359.7231-4-marek.vasut@gmail.com
State Superseded
Headers show
Series
  • [V3,1/6] PCI: rcar: Clean up remaining macros defining bits
Related show

Commit Message

Marek Vasut March 23, 2019, 1:53 a.m. UTC
From: Marek Vasut <marek.vasut+renesas@gmail.com>

Replace (8 * n) with (n << 3) to make bit shift operations consistent.
No functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Phil Edworthy <phil.edworthy@renesas.com>
Cc: Simon Horman <horms+renesas@verge.net.au>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-renesas-soc@vger.kernel.org
To: linux-pci@vger.kernel.org
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
V2: Bundle this patch with other cleanups before resending
V3: Add Wolfram's R-B
---
 drivers/pci/controller/pcie-rcar.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Comments

Geert Uytterhoeven March 25, 2019, 8:26 a.m. UTC | #1
Hi Marek,

On Sat, Mar 23, 2019 at 2:54 AM <marek.vasut@gmail.com> wrote:
> From: Marek Vasut <marek.vasut+renesas@gmail.com>
>
> Replace (8 * n) with (n << 3) to make bit shift operations consistent.
> No functional change.
>
> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>

Thanks for your patch!

Where is the inconsistency? The driver consistently uses
  1. multiplications for bit offset calculations,
  2. shifts for bit field extraction or insertion.

While technically equivalent, I think your change makes the code harder
to read: the values are multiplied by eight to convert from number of
bytes to number of bits, so IMHO "BITS_PER_BYTE * n" would be more
readable.

Gr{oetje,eeting}s,

                        Geert
Marek Vasut March 25, 2019, 11:34 a.m. UTC | #2
On 3/25/19 9:26 AM, Geert Uytterhoeven wrote:
> Hi Marek,
> 
> On Sat, Mar 23, 2019 at 2:54 AM <marek.vasut@gmail.com> wrote:
>> From: Marek Vasut <marek.vasut+renesas@gmail.com>
>>
>> Replace (8 * n) with (n << 3) to make bit shift operations consistent.
>> No functional change.
>>
>> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
> 
> Thanks for your patch!
> 
> Where is the inconsistency? The driver consistently uses
>   1. multiplications for bit offset calculations,
>   2. shifts for bit field extraction or insertion.
> 
> While technically equivalent, I think your change makes the code harder
> to read: the values are multiplied by eight to convert from number of
> bytes to number of bits, so IMHO "BITS_PER_BYTE * n" would be more
> readable.

Sure

Patch
diff mbox series

diff --git a/drivers/pci/controller/pcie-rcar.c b/drivers/pci/controller/pcie-rcar.c
index a2d3855b15ea..f835e4341590 100644
--- a/drivers/pci/controller/pcie-rcar.c
+++ b/drivers/pci/controller/pcie-rcar.c
@@ -169,7 +169,7 @@  enum {
 
 static void rcar_rmw32(struct rcar_pcie *pcie, int where, u32 mask, u32 data)
 {
-	unsigned int shift = 8 * (where & 3);
+	unsigned int shift = (where & 3) << 3;
 	u32 val = rcar_pci_read_reg(pcie, where & ~3);
 
 	val &= ~(mask << shift);
@@ -179,7 +179,7 @@  static void rcar_rmw32(struct rcar_pcie *pcie, int where, u32 mask, u32 data)
 
 static u32 rcar_read_conf(struct rcar_pcie *pcie, int where)
 {
-	unsigned int shift = 8 * (where & 3);
+	unsigned int shift = (where & 3) << 3;
 	u32 val = rcar_pci_read_reg(pcie, where & ~3);
 
 	return val >> shift;
@@ -280,9 +280,9 @@  static int rcar_pcie_read_conf(struct pci_bus *bus, unsigned int devfn,
 	}
 
 	if (size == 1)
-		*val = (*val >> (8 * (where & 3))) & 0xff;
+		*val = (*val >> ((where & 3) << 3)) & 0xff;
 	else if (size == 2)
-		*val = (*val >> (8 * (where & 2))) & 0xffff;
+		*val = (*val >> ((where & 2) << 3)) & 0xffff;
 
 	dev_dbg(&bus->dev, "pcie-config-read: bus=%3d devfn=0x%04x where=0x%04x size=%d val=0x%08lx\n",
 		bus->number, devfn, where, size, (unsigned long)*val);
@@ -308,11 +308,11 @@  static int rcar_pcie_write_conf(struct pci_bus *bus, unsigned int devfn,
 		bus->number, devfn, where, size, (unsigned long)val);
 
 	if (size == 1) {
-		shift = 8 * (where & 3);
+		shift = (where & 3) << 3;
 		data &= ~(0xff << shift);
 		data |= ((val & 0xff) << shift);
 	} else if (size == 2) {
-		shift = 8 * (where & 2);
+		shift = (where & 2) << 3;
 		data &= ~(0xffff << shift);
 		data |= ((val & 0xffff) << shift);
 	} else