Subject: Re: [PATCH][PPC32] Marvell host bridge support (mv64x60)

From: "Mark A. Greer" <[email-masked]>
Date: Mon, 22 Nov 2004 11:40:45 -0700

Andrew Morton wrote:

>"Mark A. Greer" <[email-masked]> wrote:
>  
>
>>This patch adds core support for a line of host bridges from Marvell 
>>(formerly Galileo).  This code has been tested with a GT64260a, 
>>GT64260b, MV64360, and MV64460.  Patches for platforms that use these 
>>bridges will be sent separately.
>>
>>    
>>
>
>Shouldn't these guys:
>
>
>+       u32     cpu2mem_tab[MV64x60_CPU2MEM_WINDOWS][2] = {
>+                       { MV64x60_CPU2MEM_0_BASE, MV64x60_CPU2MEM_0_SIZE },
>+                       { MV64x60_CPU2MEM_1_BASE, MV64x60_CPU2MEM_1_SIZE },
>+                       { MV64x60_CPU2MEM_2_BASE, MV64x60_CPU2MEM_2_SIZE },
>+                       { MV64x60_CPU2MEM_3_BASE, MV64x60_CPU2MEM_3_SIZE }
>+       };
>+       u32     com2mem_tab[MV64x60_CPU2MEM_WINDOWS][2] = {
>+                       { MV64360_MPSC2MEM_0_BASE, MV64360_MPSC2MEM_0_SIZE },
>+                       { MV64360_MPSC2MEM_1_BASE, MV64360_MPSC2MEM_1_SIZE },
>+                       { MV64360_MPSC2MEM_2_BASE, MV64360_MPSC2MEM_2_SIZE },
>+                       { MV64360_MPSC2MEM_3_BASE, MV64360_MPSC2MEM_3_SIZE }
>+       };
>+       u32     dram_selects[MV64x60_CPU2MEM_WINDOWS] = { 0xe, 0xd, 0xb, 0x7 };
>
>be static, and maybe __devinitdata?  Right now, the CPU has to populate
>them by hand at runtime.
>

Yes.  I'll fix that.

>
>+wait_for_ownership(int chan)
>+{
>+	int	i;
>+
>+	for (i=0; i<MAX_TX_WAIT; i++) {
>+		if ((MV64x60_REG_READ(sdma_regs[chan].sdcm) &
>+				SDMA_SDCM_TXD) == 0)
>+			break;
>+
>+		udelay(1000);
>
>ow, big busywait.  Can't use a sleep in here?  I guess not :(
>

This code is in the ppc bootwrapper which is glue code to get the
hardware (and bd_info, etc.) from whatever state the f/w left it in into
something the kernel can work with.  IOW, its not in the kernel and
there is no sleep mechanism...or even a thread/process entity to put to
sleep.

>+ * arch/ppc/boot/simple/mv64x60_tty.c
>
>hm.  Normally we put arch-specific drivers like this into drivers/serial
>and do the appropriate Kconfig work.  Is there a reason why this serial
>driver is buried under arch/ppc?
>

It isn't a part of the kernel so I don't think it belongs in
drivers/serial.  This particular serial driver is required for cmd_line
editing when booting a zImage.

>+#include "../../../../drivers/serial/mpsc_defs.h"
>
>erk.
>

Ah, yeah, I'll fix that too :)

>
>+struct mv64x60_rx_desc {
>+	volatile u16 bufsize;
>+	volatile u16 bytecnt;
>+	volatile u32 cmd_stat;
>+	volatile u32 next_desc_ptr;
>+	volatile u32 buffer;
>+};
>+
>+struct mv64x60_tx_desc {
>+	volatile u16 bytecnt;
>+	volatile u16 shadow;
>+	volatile u32 cmd_stat;
>+	volatile u32 next_desc_ptr;
>+	volatile u32 buffer;
>+};
>
>Do these need to be volatile?  If so, it indicates that the driver is doing
>something wrong.
>

I didn't spend much time looking at this code.  I'll clean it up.

>
>+gt64260_register_hdlrs(void)
>+{
>+	/* Register CPU interface error interrupt handler */
>+	request_irq(MV64x60_IRQ_CPU_ERR, gt64260_cpu_error_int_handler,
>+		    SA_INTERRUPT, CPU_INTR_STR, 0);
>
>request_irq() can fail.
>

OK.

>+int
>+mv64360_get_irq(struct pt_regs *regs)
>+{
>+	int irq;
>+	int irq_gpp;
>+
>+#ifdef CONFIG_SMP
>+	/*
>+	 * Second CPU gets only doorbell (message) interrupts.
>+	 * The doorbell interrupt is BIT28 in the main interrupt low cause reg.
>+	 */
>+	int cpu_nr = smp_processor_id();
>
>This function has no callers, so I am unable to determine whether it is
>called from non-preemptible code.  If it is called from preemptible code
>then that smp_processor_id() is buggy, because you can switch CPUs at any
>time.
>

Its called via ppc_md.get_irq() (see arch/ppc/kernel/irq.c:do_IRQ()).
ppc_md.get_irq is set up in the platform files.

>+static struct platform_device mpsc_shared_device = { /* Shared device */
>+	.name		= MPSC_SHARED_NAME,
>+	.id		= 0,
>+	.num_resources	= ARRAY_SIZE(mv64x60_mpsc_shared_resources),
>+	.resource	= mv64x60_mpsc_shared_resources,
>+	.dev = {
>+		.driver_data = (void *)&mv64x60_mpsc_shared_pd_dd,
>+	},
>+};
>
>The cast to void* is unnecessary.
>

OK.

>+	(void)mv64x60_setup_for_chip(&bh);
>
>how come you always stick that (void) in there?
>

I did that b/c the routine returns an 'int' but I'm ignoring it.  I
probably shouldn't be ignoring it...

>
>+mv64x60_config_cpu2mem_windows(struct mv64x60_handle *bh,
>+	struct mv64x60_setup_info *si,
>+	u32 mem_windows[MV64x60_CPU2MEM_WINDOWS][2])
>+{
>+	u32	i, win;
>+	u32	prot_tab[] = {
>+			MV64x60_CPU_PROT_0_WIN, MV64x60_CPU_PROT_1_WIN,
>+			MV64x60_CPU_PROT_2_WIN, MV64x60_CPU_PROT_3_WIN
>+		};
>+	u32	cpu_snoop_tab[] = {
>+			MV64x60_CPU_SNOOP_0_WIN, MV64x60_CPU_SNOOP_1_WIN,
>+			MV64x60_CPU_SNOOP_2_WIN, MV64x60_CPU_SNOOP_3_WIN
>+		};
>
>static initialisation?
>

Yep.

>
>+mv64x60_config_cpu2pci_windows(struct mv64x60_handle *bh,
>+	struct mv64x60_pci_info *pi, u32 bus)
>+{
>+	int	i;
>+	u32	win_tab[2][4] = {
>+			{ MV64x60_CPU2PCI0_IO_WIN, MV64x60_CPU2PCI0_MEM_0_WIN,
>+			  MV64x60_CPU2PCI0_MEM_1_WIN,
>+			  MV64x60_CPU2PCI0_MEM_2_WIN },
>+			{ MV64x60_CPU2PCI1_IO_WIN, MV64x60_CPU2PCI1_MEM_0_WIN,
>+			  MV64x60_CPU2PCI1_MEM_1_WIN,
>+			  MV64x60_CPU2PCI1_MEM_2_WIN },
>+		};
>+	u32	remap_tab[2][4] = {
>+			{ MV64x60_CPU2PCI0_IO_REMAP_WIN,
>+			  MV64x60_CPU2PCI0_MEM_0_REMAP_WIN,
>+			  MV64x60_CPU2PCI0_MEM_1_REMAP_WIN,
>+			  MV64x60_CPU2PCI0_MEM_2_REMAP_WIN },
>+			{ MV64x60_CPU2PCI1_IO_REMAP_WIN,
>+			  MV64x60_CPU2PCI1_MEM_0_REMAP_WIN,
>+			  MV64x60_CPU2PCI1_MEM_1_REMAP_WIN,
>+			  MV64x60_CPU2PCI1_MEM_2_REMAP_WIN }
>+		};
>+
>
>ditto
>
>
>+mv64x60_config_pci2mem_windows(struct mv64x60_handle *bh,
>
>and here
>
>+mv64360_set_pci2mem_window(struct pci_controller *hose, u32 bus, u32 window,
>
>and here
>
>+mv64360_config_io2mem_windows(struct mv64x60_handle *bh,
>
>and here

Yes, several times.  I'll fix it.

>
>Anyway, I'll stick this as-is in -mm.  Feel free to send an incremental
>patch, or a replacement.
>

Thanks for the feedback.  I'll clean it up & resend.

Mark