Re: [PATCH v3 1/2] ata: pata_falcon: fix IO base selection for Q40

Michael Schmitz
2023-08-21T23:57:29Z

Hi Geert,

On 21/08/23 19:50, Geert Uytterhoeven wrote:
> Hi Michael,
>
> On Sat, Aug 19, 2023 at 1:49 AM Michael Schmitz <schmitzmic@gmail.com> wrote:
>> With commit 44b1fbc0f5f3 ("m68k/q40: Replace q40ide driver
>> with pata_falcon and falconide"), the Q40 IDE driver was
>> replaced by pata_falcon.c.
>>
>> Both IO and memory resources were defined for the Q40 IDE
>> platform device, but definition of the IDE register addresses
>> was modeled after the Falcon case, both in use of the memory
>> resources and in including register scale and byte vs. word
>> offset in the address.
>>
>> This was correct for the Falcon case, which does not apply
>> any address translation to the register addresses. In the
>> Q40 case, all of device base address, byte access offset
>> and register scaling is included in the platform specific
>> ISA access translation (in asm/mm_io.h).
>>
>> As a consequence, such address translation gets applied
>> twice, and register addresses are mangled.
>>
>> Use the device base address from the platform IO resource,
>> and use standard register offsets from that base in order
>> to calculate register addresses (the IO address translation
>> will then apply the correct ISA window base and scaling).
>>
>> Encode PIO_OFFSET into IO port addresses for all registers
>> except the data transfer register. Encode the MMIO offset
>> there (pata_falcon_data_xfer() directly uses raw IO with
>> no address translation).
>>
>> Reported-by: William R Sowerbutts <will@sowerbutts.com>
>> Closes: https://lore.kernel.org/r/CAMuHMdUU62jjunJh9cqSqHT87B0H0A4udOOPs=WN7WZKpcagVA@mail.gmail.com
>> Link: https://lore.kernel.org/r/CAMuHMdUU62jjunJh9cqSqHT87B0H0A4udOOPs=WN7WZKpcagVA@mail.gmail.com
>> Fixes: 44b1fbc0f5f3 ("m68k/q40: Replace q40ide driver with pata_falcon and falconide")
>> Cc: stable@vger.kernel.org
>> Cc: Finn Thain <fthain@linux-m68k.org>
>> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
>> Tested-by: William R Sowerbutts <will@sowerbutts.com>
>> Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
> Thanks for the update!
>
>> --- a/drivers/ata/pata_falcon.c
>> +++ b/drivers/ata/pata_falcon.c
>> @@ -165,26 +165,39 @@ static int __init pata_falcon_init_one(struct platform_device *pdev)
>> ap->pio_mask = ATA_PIO4;
>> ap->flags |= ATA_FLAG_SLAVE_POSS | ATA_FLAG_NO_IORDY;
>>
>> - base = (void __iomem *)base_mem_res->start;
>> /* N.B. this assumes data_addr will be used for word-sized I/O only */
>> - ap->ioaddr.data_addr = base + 0 + 0 * 4;
>> - ap->ioaddr.error_addr = base + 1 + 1 * 4;
>> - ap->ioaddr.feature_addr = base + 1 + 1 * 4;
>> - ap->ioaddr.nsect_addr = base + 1 + 2 * 4;
>> - ap->ioaddr.lbal_addr = base + 1 + 3 * 4;
>> - ap->ioaddr.lbam_addr = base + 1 + 4 * 4;
>> - ap->ioaddr.lbah_addr = base + 1 + 5 * 4;
>> - ap->ioaddr.device_addr = base + 1 + 6 * 4;
>> - ap->ioaddr.status_addr = base + 1 + 7 * 4;
>> - ap->ioaddr.command_addr = base + 1 + 7 * 4;
>> -
>> - base = (void __iomem *)ctl_mem_res->start;
>> - ap->ioaddr.altstatus_addr = base + 1;
>> - ap->ioaddr.ctl_addr = base + 1;
>> -
>> - ata_port_desc(ap, "cmd 0x%lx ctl 0x%lx",
>> - (unsigned long)base_mem_res->start,
>> - (unsigned long)ctl_mem_res->start);
>> + ap->ioaddr.data_addr = (void __iomem *)base_mem_res->start;
>> +
>> + if (base_res) { /* only Q40 has IO resources */
>> + io_offset = 0x10000;
>> + reg_scale = 1;
>> + base = (void __iomem *)base_res->start;
>> + ctl_base = (void __iomem *)ctl_res->start;
>> +
>> + ata_port_desc(ap, "cmd %pa ctl %pa",
>> + &base_res->start,
>> + &ctl_res->start);
> This can be moved outside the else, using %px to format base and
> ctl_base.

Right - do we need some additional message spelling out what address Q40
uses for data transfers? (Redundant for Falcon, of course ...)

Though that could be handled outside the else, too:

ata_port_desc(ap, "cmd %px ctl %px data %pa",
base, ctl_base, &ap->ioaddr.data_addr);

Cheers,

Michael

>> + } else {
>> + base = (void __iomem *)base_mem_res->start;
>> + ctl_base = (void __iomem *)ctl_mem_res->start;
>> +
>> + ata_port_desc(ap, "cmd %pa ctl %pa",
>> + &base_mem_res->start,
>> + &ctl_mem_res->start);
>> + }
> Gr{oetje,eeting}s,
>
> Geert
>