Hi Arnd,
Am 11.06.24 um 14:14 schrieb Arnd Bergmann:
On Tue, Jun 11, 2024, at 13:37, Stefan Wahren wrote:
Am 11.06.24 um 13:08 schrieb Arnd Bergmann:
On Tue, Jun 11, 2024, at 12:47, Stefan Wahren wrote:
if (len == 0)
pr_warn_once("%s: sg_dma_len() == 0\n", __func__);
else if (i && (i != (dma_buffers - 1)) && (len & ~PAGE_MASK))
pr_warn_once("%s: following block not page aligned\n",
__func__);
else if (i && (addr & ~PAGE_MASK)) {
pr_warn_once("%s: block %u, DMA address %pad doesn't align
with PAGE_MASK 0x%lx\n", __func__, i, &addr, PAGE_MASK);
pr_warn_once("sg_dma_is_swiotlb: %d, dma_flags: %x\n",
sg_dma_is_swiotlb(sg), sg->dma_flags);
pr_warn_once("type = %s\n", (type == PAGELIST_WRITE) ?
"PAGELIST_WRITE" : "PAGELIST_READ");
if (buf)
pr_warn_once("buf = %p, count = %zu\n", buf, count);
else
pr_warn_once("ubuf = %p, count = %zu\n", ubuf, count);
}
Output:
[ 66.184030] create_pagelist: block 1, DMA address 0x00000000f5fc7800
doesn't align with PAGE_MASK 0xfffffffffffff000
[ 66.184056] sg_dma_is_swiotlb: 0, dma_flags: 0
[ 66.184063] type = PAGELIST_READ
[ 66.184066] ubuf = 00000000266a70a7, count = 0
sorry my debug attempt for count was pointless. The value is always
decremented to zero at this point. So your suggested change won't have
any effect.
From my reading of the code, it's not really meant to handle
count=0, so maybe the answer for that is to just return an
error (or possibly success) when there is data attached to
the request from user space, something like
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_dev.c
@@ -328,6 +328,11 @@ static int vchiq_irq_queue_bulk_tx_rx(struct vchiq_instance *instance,
userdata = args->userdata;
}
+ if (!args->size) {
+ ret = 0;
+ goto out;
+ }
+
status = vchiq_bulk_transfer(instance, args->handle, NULL, args->data, args->size,
userdata, args->mode, dir);
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