Re: [RFC 13/13] scsi: megaraid: Make use of dev_64bit_mmio_supported()
From: Arnd Bergmann
Date: Fri Feb 26 2021 - 13:08:13 EST
On Fri, Feb 26, 2021 at 3:30 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
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On Fri, Feb 26, 2021 at 3:03 PM Nicolas Saenz Julienne
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<nsaenzjulienne@xxxxxxx> wrote:
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> unsigned long flags;
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> - spin_lock_irqsave(&instance->hba_lock, flags);
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> - writel(le32_to_cpu(req_desc->u.low),
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> - &instance->reg_set->inbound_low_queue_port);
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> - writel(le32_to_cpu(req_desc->u.high),
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> - &instance->reg_set->inbound_high_queue_port);
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> - spin_unlock_irqrestore(&instance->hba_lock, flags);
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> +
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> + if (dev_64bit_mmio_supported(&instance->pdev->dev)) {
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> + writeq(req_data, &instance->reg_set->inbound_low_queue_port);
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> + } else {
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> + spin_lock_irqsave(&instance->hba_lock, flags);
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> + lo_hi_writeq(req_data, &instance->reg_set->inbound_low_queue_port);
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> + spin_unlock_irqrestore(&instance->hba_lock, flags);
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> + }
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I see your patch changes the code to the lo_hi_writeq() accessor,
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and it also fixes the endianness bug (double byteswap on big-endian),
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but it does not fix the spinlock bug (writel on pci leaks out of the lock
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unless it's followed by a read).
On second look, it seems your patch breaks the byteorder logic,
rather than fixing it. It would seem better to leave it unchanged
then, or to send a separate rework of the endianness conversion if
you think it is wrong.
Arnd